Reynolds ‘531’

Note: VCC has shut down access to their catalogs except to members so some links will be broken.

If you found this page you probably stumbled across it searching for Reynolds ‘531’ (say it five-three-one). Because there is often confusion about Reynolds ‘531’ and inaccurate information, even from cycling publications, this is an attempt to compile information about Reynolds ‘531’ based mostly on official Reynolds publications with minimal reliance on secondary and tertiary sources, and a work in progress rather than just copying and pasting other articles. This does not necessarily reflect the comprehensive range of Reynolds ‘531’ and some sources seem to indicate special ‘531’ available, but it is difficult to separate good secondary and tertiary information from bad. Some may claim to have information with great authority, but assert without apparent basis. I have attempted to verify as much information here as possible, and speculation on this page is just that, speculation. Price lists sometimes indicate additional options not found in the catalogs. Reynolds also accepted custom orders, but due to high tooling costs, this likely would have only been for large volumes and found on high production frames, well documented advertised, or hidden if it could be interpreted as bad (heavier tubes) and not the occasional one-off unless it was for R&D or trade show purposes, in which case it would be advertised as unusual.

Table of Contents

• FAQ
• Identifying 531 Decals at a Glance
• Reynolds in the 20’s
• Reynolds ‘531’ in the 30’s
• Reynolds “531” in the 40’s
• Reynolds ‘531’ in the 50’s
• Reynolds ‘531’ in the 60’s
• Reynolds 531 in the 70’s
• Reynolds 531 in the 80’s
• Reynolds 531 in the 90’s
• Reynolds 531 by any other name
• Reynolds 653
• Reynolds 753
• Reynolds 531 oddities
• The End
• NOS 531 Measurements and Framebuilder Info
• The French 3/10 Mystery
• The competition

FAQ

What is Reynolds ‘531’?
Reynolds ‘531’ (say it five-three-one) is an aircraft–grade manganese-molybdenum steel designed for brazing that was developed by Reynolds in 1935 as a higher strength alternative to hi-tensile steel of the time. It allowed for lighter tubes with thinner walls and was available in both plain gauge (constant wall thickness) and butted (variable wall thickness) forms. It, and the heat-treated version, 753, were considered the premium frame materials prior to widespread adoption of carbon fiber and aluminum frames and boast more Tour de France wins than any other material. It was also utilized in race cars, motorcycles (the famous Norton Manx featherbed frame) and fighter planes (presumably the Spitfire as Reynolds is known to have stopped bicycle tubing production to make wing spars for it in WWII). The name is derived from the ratio of alloying elements, presumably Mn, C and Mo (note that S and P are trace impurities, not alloying elements). Another claim is that the name comes from the tensile strength being 53 tons/in², but this is dubious since most literature claims 50 tons/in². The composition is:

C	0.23 – 0.29 %
Si	0.15 – 0.35%
Mn	1.25 – 1.45%
Mo	0.15 – 0.25%

It is not a chromium-molybdenum (a.k.a CrMo) steel due to lack of any chromium in the formulation. ‘531’ had superior strength after brass brazing compared to CrMo in the heat affected zone. However, ‘531’ was designed for brazing so production was shifted towards other alloys (such as CrMo) due to the shift away from brazed frames to welded steel and other frame materials.

Where can I get Reynolds ‘531’?
Reynolds ‘531’ is found on high quality classic and vintage steel frames. Reynolds has only produced ‘531’ in recent history for their anniversary and large special orders due to the ‘531’ alloy being proprietary and requiring a large custom melt of the raw steel. Double butted 0.8mm/0.5mm/0.8mm (actual) Reynolds ‘531’ frame tubes can be purchased from Strawberry Cycles. This tubing is thinner and lighter than most historical ‘531’ tubing (see below). Forks and stays are not available. Pashley is one of the few manufacturing using ‘531’ for their vintage inspired bicycles. Replica and replacement decals are available from Reynolds or H. Lloyd Cycles. If you want a decal to match the new frame tubes, the only appropriate decal is the French “3 tubes” decal. I am not affiliated with any of these companies, their mention is solely for your convenience.

What’s with the single quotations marks around ‘531’?
I don’t know. It’s a thing Reynolds used to do, I speculate it is an attempt to signify that ‘531’ is a brand name rather than a standards designation. Reynolds eventually stopped and apparently started calling it 531 without the single quotation marks in the 70’s.

How thick is ‘531’?
‘531’ was available in various gauges, with various tubed grouped together to form various tubesets often signified with different decals. Prior to tubeset decals, there were a limited number of widely available tubing options. Thicknesses vary even within a tubeset as Reynolds, unlike other manufacturers, preferred not only a larger diameter downtube but also one with thicker walls in almost all of their premium tubesets. Note that some sources give thicknesses in nominal metric dimensions, and French sources will list thickness as fractional tenth of a millimeter. However, Reynolds used to draw tubes to SWG thicknesses (not BWG despite being in Birmingham) with a nominal metric conversion that is not very accurate. There are some rumors of 3/10 (0.38mm) ‘531’ but I have found it difficult to find official Reynolds publications to corroborate this. For convenience nominal metric dimensions will be used with 1 representing 1.0 nominal, 9 representing 0.9 nominal, 8 representing 0.8 nominal and so on despite the inaccuracy in the form 8/5/8 meaning a double butted tube with ends that are 0.81mm thick and centers that or 0.56mm thick. See table for accurate conversion of SWG to millimeters:

SWG	Nominal(mm)	Actual(mm)
18	1.2	1.22
19	1.0	1.02
20	0.9	0.91
21	0.8	0.81
22	0.7	0.71
23	0.6	0.61
24	0.5	0.56
26	0.4	0.46
28	0.3	0.38

For a regular 531 decal, if the frame is for a fast or racing type of bicycle, chances are it has a 0.81/0.56/0.81 top tube, 0.81/0.56 seat tube and 0.91/0.61/0.91 down tube. This seems to correspond with the various Reynolds catalogs, and mentioned as the norm in the The Proteus Framebuilding Book (who was the only U.S. Reynolds agent according to The Custom Bicycle). For a touring or sport touring frame, one or more of the tubes may be substituted with a 1.02/0.71/1.02 frame. It may be just the downtube (531 special tourist), the downtube and top tube, or all three main tubes (531 super tourist). It has also been claimed that many production or semi-production frames have been made with 1/7/1 tubes. Supposedly Richard Schwinn of Paramount Bicycles has said Paramounts were made with the 1/7/1 tubes, but this is unverified, and The Custom Bicycle states that Paramounts of the period were made with a heavier than standard and boggling 1.2/8/1.2 top tube, 1/7/1 down tube and supposedly 1.2/9 taper gauge chainstays. This is stout tubing, thicker than many plain gauge cr-mo tubes.

French decals present a conundrum. If Daniel Rebour is to be believed, Dupieux the agent and importer of Reynolds in France custom specified the tubes for the French market. Even though the English Reynolds catalogs state availability in French diameters, it may be that French availability was more determined by Dupieux’s stock than Reynold’s conventions. Rebour claims that the French Reynolds tubes were 1/7/1, 7/5/7, 7/3/7 and 8/5 for the seat tube. Peugeot, once the largest user of Reynolds tubes in Europe, released various versions of various bicycles domestically and for export. Some catalogs state the PX-10 at least in some markets and some years used 7/10 tubing. Others claim the PS-10 used 7/10 in all the main tubes, despite using the same seatpost as an 8/5 seat tube. Some catalogs state the PY-10 uses 5/10 tubing, and oddly enough the German catalog shows the PY-10 with the red 531EL(SL) decal despite listing a 5/10 top tube and 7/10 downtube for stability. This would be much closer to 531ST spec than 531SL. Note that the PY-10 was a semi-custom line, and that the bike could have been tailored for market preferences. While some catalogs list 3/10 tubing available as a custom option for the PY-10, this seems to be only after the introduction of 753. It should be noted that the models varied from market to market. It is possible that 5/10 just refers to the top tube, and the 7/10 downtube in German PY-10s was to add stiffness over the typical 9/6/9 tube. It does mark an odd departure from 531SL decal usage though, when Reynolds was only selling them as complete box sets, but perhaps the marketing people were confused and the PY-10 made with 7/10 downtubes never made it off the factory floor with 531EL decals, or perhaps not. The Custom Bicycle notes that 7/10 tubing is only used in unusual cases for PY-10’s. The Peugeot catalogs can be interpreted as supporting Rebour’s understanding of French 531, or as a reflection of their often confused and eclectic marketing and offerings. It may be the case that Dupieux was running a very different operation in France, selling only non-standard tubes in metric diameters and different gauges, exclusive to him and dictating or allowing different decal usage than Birmingham. More research is required and any French Reynolds catalog of pricelists would aid in interpreting the French Reynolds market. Pictures of tube stampings on French frames would also help.

What are the butting profiles?
Multiple diagrams I have come across indicate that there is a 75mm butt, 51mm tapers, and 280mm center for double butted tubes, although this is usually without reference to what tube. The same measurements for the butts and tapers but in inches seem to be used in the 20’s. This seems to have applied even towards the 00’s.Tubing would be cut down to size off the long butt. It may be universally applicable to 531, but Reynolds claims weight savings for 753 vs 531 of the same thickness, so the butt profile for 753 may differ.

When was my tubeset made?
Reynolds has this document listing the dates and descriptions of various tubesets. Note that I have spotted a few discrepancies between information in this document and contemporaneous literature. This document may also help identify the era and tubeset

Identifying 531 Decals at a Glance

Reynolds decals went through several iterations and while Reynolds and H. Lloyd have put together their own timelines, a simplified timeline of 531 butted tubes, forks and stays decals is shown here. Note that manufacturers may have used older decals from older tubing stock than the dates shown here for any given year of production.

Traditional 70’s and earlier decals can generally easily and quickly be identified, even if most of the decal is missing, as they often tend to be. Sometimes it may be impossible to read the decal in a photo. There are also many variants that may differ in small details. 80’s and later decals changed and require closer inspection.

Butted frame tubes, forks and stays

Typically “531” in green overlaid by “Butted” or “Reynolds” in gold will be printed diagonally from the bottom left corner to the top right corner. The top left corner will have three words each on a separate line (“Guaranteed Built With” or the French equivalent) in gold and three more lines in gold on the bottom right corner (“Butted Tubes, Forks & Stays” or the French Equivalent). Outline in gold and on a black background.

However it is not unusual to find a lower end Raleigh using this decal but with some words blacked out, as these were apparently used as a substitute and modified when they ran out of the correct decal.

Another variant is the “stars” decal. 531 will be in green, with two green stars on each side.

If you can spot any one of the these three characteristics on a decal, it is most likely full butted 531. Caveat emptor decals with words blacked out, especially Raleighs.

• Diagonal “Reynolds” in gold and “531” in green or
• Three lines of gold text in the top left or bottom right corner or
• Green stars to the left or right of horizontal “531“
• Check to see if any words are blacked out especially on Raleighs

Butted frame tubes

“531” in green overlaid by “Butted” or “Reynolds” in gold will be printed horizontally, with either “Butted” or “Reynolds” in gold overlaid. There will be horizontal gold text above and below. Outline and text in gold and on a black background.

If you can spot any one of the these two patters, it most likely has a butted 531 front triangle.

• Horizontal “531” in green overlaid by “Butted” in gold
• Horizontal “531” in green overlaid by “Reynolds” in gold on a French* bike

Note that these frames are not necessarily inferior as Reynolds 531 stays were generally not butted. However 531 fork blades are generally superior due to being taper gauge, so check for fork decals. Technically these decals are not the same, the English decal signifies a 531 head tube, the French one does not because it may substitute a non-Reynolds metric head tube.

*Do not confuse the French decal with the rare English “Plain Gauge tubes, Forks & Stays” decal, as seen below.

Plain Gauge frame tubes

Typically “531” in green will be printed horizontally with no gold text overlaid. “Reynolds” in gold will be printed above “531” and “Frame Tubing” or similar in gold will be printed below.

• If the green 531 is horizontal and there is no gold text overlaid, and no green stars the frame most likely has plain gauge main tubes.

See the previous section for the “Plain Gauge tubes, Forks & Stays” variant, which supposedly has plain gauge 531 fork blades without fork decals.

531 Special Lightweight

Similar to the “Butted Frame Tubes, Forks & Stays” decals, but “531” is in red, “Reynolds” is in green and the text in the top left is different.

• If the decal says “531” in red overlaid by “Reynolds” in green, the frame and fork are most likely 531SL.

Fork Decals

Typical Reynolds fork decals are an inverted triangle, text and outline in gold and 531 in green on a black background.

Variants include the rare S.R. (super resilient) fork blades which will say “S.R.” and the square/shield 531SL decal in green, red and gold on a black background. The 531SL fork decals will only ever be paired with a 531SL frame decal.

Reynolds in the 20’s

‘531’ didn’t exist yet. Here’s a link to a 1920’s catalog. Some period advertisements can also be found at this link. (Mirrored here as a backup only)

Reynolds ‘531’ in the 30’s

Reynolds 531 is first introduced in 1935 as stronger alternative to Reynolds H.M. tubing. Here’s a link containing several 1930’s advertisements

Reynolds “531” in the 40’s

This is the earliest decade I have found a Reynolds catalog and price list with “531” thus far. Some sources say that prior to tubesets, framebuilders would pick and choose tubes from a Reynolds catalog. While this is true in a sense, note that Reynolds only really shows one normal set of butted “531” frame tubes which is equivalent to later 531c frame tubes. Other tubes are specialty tubes. The thicker 1/7/1 butted down tube found in Special Tourist and Super Tourist tubesets are not found, rather tubes of that gauge can be found as Reynolds A. Additional tubing may have been produced for non-bicycle usage which may be the source of custom bicycles with especially light tubing. There are however a large variety of stays to choose from.

Reynolds released a heat-treated version of “531”, a precursor to 753. Benefits listed are improved fatigue resistance and ease of manufacturing, not improved strength, however UTS is identical to 70’s 753. Reynolds was apparently sitting on 753 for decades, it was just that they couldn’t take advantage of it because the bronze brazing techniques common for the time would ruin the temper.

Reynolds “531” frame tubes

Note that according to the price lists, “531” is offered in 0.71 plain gauge and offered the following butted gauges. It also lists some 531 tubes for “Sif Bronze Welded Frames” and there tandem tubes. Thicker plain gauge and butted tubes are available in H.M. (high manganese), A and B (hi-tensile). The thinnest walls of “531” are not actually any thinner than H.M. at 0.56mm, but Reynolds felt that “531” justified a lighter downtube and thinner butts for the seat tube and top tube. There was a 28.6 diameter 8/5/8 tube for use as a bronze welded top tube and a tandem rear downtube, but Reynolds never felt the need to spec this as a normal downtube.

Considering that 0.7 was the thickness of the thin butts of 531SL, 531Pro and 753, and lies in the middle of the thick butts and thin middles of the butted tubes, it is remarkably thin for plain gauge (although not nearly as thin as Columbus Record).

Tube	Diameter	Length	Thick	Thin
Top	25.4	610	0.81	0.56
Top B	25.4	610	1.02	0.71
Top B/Down T	28.6	610	0.81	0.56
Down	28.6	610	0.91	0.61
Down T	31.7	537	1.22	0.81
Down T PG	31.7	537	0.91
Seat	28.6	610	0.81	0.56
Seat B L	28.6	610	0.91	0.61
Seat B H	28.6	610	1.02	0.71
Bottom T	38.1	533	1.02	0.71
Bottom T PG	38.1	533	0.91
Top PG	25.4	610	0.71
Down PG	28.6	610	0.71
Seat PG	22.2	610	0.71
Head	31.7	610	0.71

Reynolds “531” steerers

“531” steerers were only available in 1.63/2.34 in lengths 203-406 by the inch. The butt was 51mm or 102mm and the taper 38mm. They were available threaded and with the option for slotting for clip headsets (the headset contained a clamp that would clamp down on the steerer and hold the stem instead of the stem having an expander). There was also a thicker tandem steerer.

Tube	Diameter	Length	Butt	Taper	Thick	Thin
Steerer	25.4	203-406	51/102	38	2.34/3.25	1.63

Reynolds “531” chainstays

Chainstays were offered in a variety of styles, round oval to round (this appears to be simply pressed flat, not like modern ROR), oval to round, round-D-round, round with long taper, fluted or indented for clearance, and rapid taper, which was full diameter for the first 51mm, then tapered down for the next 51mm to 11.4mm until the end. There were also options for doming and slotting for an additional fee. The only length shown for chainstays is 406mm for rapid taper stays which seems short to me. Each diameter was offered in three different wall thicknesses. Note that wall thicknesses listed are options, not butts.

Tube	Diameter	Length	Thickness
3/4″	19.1	11.1/9.5/11.4(I/D)	1.42/1.22/0.81
7/8″	22.2	11.1/9.5/11.4(I/D)	1.22/1.02/0.71
Rapid Taper	19.1/22.2	11.4
Tandem	22.2	15.9	1.22

Reynolds “531” seatstays

The double taper seatstay was offered only in “531” and unlike modern double taper seat stays, it had no constant diameter center. There was also the “pencil thin” stay, really 11.1mm which stopped being listed in catalogs in later decades. They could be domed and slotted for an additional fee. It is unclear is all thicknesses were available for “531” of if certain thicknesses corresponded with different steels. Note that wall thicknesses listed are options, not butts.

Tube	Diameter	Length	Tip O/D	Thickness
7/16″	11.1	610	8.0	1.22
1/2″	12.7	610	8.0	1.02/0.91/0.71
79/128″	15.7	610	8.0/9.5	0.91/0.81/0.71
79/128″	15.7	610	9.5 (I/D)	0.81/0.71
Double Taper	12.2→14.5	584	7.9	0.71
Tandem	17.0	438	12.7	0.81

Reynolds “531” fork blades

Pre-raked forks were available in a variety of bend radii and offsets from 44mm to 70mm. Length was 406mm with a parallel section at the top 89mm long except for the 70mm offset one which was 76mm. Tips could be processed at the Reynolds factor for an additional fee.

There is also the rather confusing “Super Resilient” fork blade that dates back to at least the 30’s. It is listed as “18-17-20g” which corresponds to 1.22/1.42/0.91mm (actual). The cross section seems to show a thicker wall in the middle of the blade before the rake. Perhaps it is designed to be rigid in both the top and the taper of the blade and flex only at the tip. Perhaps it maintained extra thickness in the middle for clamp on cantilever brakes. According to price lists, it is more expensive than a normal taper gauge blade, but it does not seem to be a lighter blade based on the fact “Super Resilient” blades can also be made from Reynolds A and H.M. (high manganese, the predecessor to “531”).

It seems that they may be the blades designed prior to “531” for Ernest F. Russ (who also claims to have invented the rapid taper chainstay) for the purpose of creating a stronger fork blade with flex isolated at the tip. He describes how the fork is strong enough to survive a car crash and bend the frame instead. Alternatively, shop lore could be filled with half truths as it often is. Common shop lore says S.R. blades were extra resilient, often interpreted as flexible, especially at the tips. It may have been designed to be extra flexible at one point — relative to a 7/8″ blade 1.4mm wall, but flexible at the crown, not the tip, due to the thinner wall at the crown end. The extra flexibility may have already been outdated by the 40’s when lighter thinner fork blades were being made, such as the 7/8″ 1.2mm blades seen below (there were also thin wall blades int he 20’s), and the S.R. blade was merely a lighter extra strong blade that could still take clamp on cantilevers like Resilions (among the best brakes in the 30’s) or other clamp on brakes and was an expensive compromise between 1.2mm and 1.4mm fork blades.

Tube	Shape	Tip I/D	Thick	Thin
Round	22.2	11.3/10.2/8.9	1.42	0.91
D-shape L	29.3×15.9 (22.2)	11.3/10.2/8.9	1.22	0.81
D-shape H	29.3×15.9 (22.2)	11.3/10.2/8.9	1.42	0.91
D-shape PG	29.3×15.9 (22.2)	11.3/10.2/8.9	1.22
D Tandem	29.3×15.9 (22.2)	11.8	1.42	0.91/1.42
Continental L	28.6×15.9 (23.1)	11.3/10.2/8.9	1.22	0.81
Continental H	28.6×15.9 (23.1)	11.3/10.2/8.9	1.42	0.91
Continental PG	28.6×15.9 (23.1)	11.3/10.2/8.9	1.22
Brampton L	29.8×13.3	11.3/10.2/8.9	1.22	0.81
Brampton H	29.8×13.3	11.3/10.2/8.9	1.42	0.91
Brampton PG	29.8×13.3	11.3/10.2/8.9	1.22
S.R. Round	22.2		1.22→1.42	0.91
S.R. D-shape	29.3×15.9		1.22→1.42	0.91

Reynolds Components

Reynolds also manufactured a number of cycling components in both steel and aluminum. There were stems made from 531, but also alloy handlebars, seatposts, and stems utilizing Reynolds’ expertise in metal tubing. Note how the stem consists of an extension fitted on a tube with a tapered end rather than the entire stem being forged or cast in one piece. The diagram shows a stem for a head clip style stem which is why the bolt does not pass through the entire length of the stem.

Reynolds ‘531’ in the 50’s

Elsewhere this catalog is said to be 70’s or other dates, but I am inclined to to date it as 50’s or 60’s based on the inclusion of Reynolds A butted hi-tensile tubing. Another copy of this catalog with price list has been dated to 1956.

Reynolds ‘531’ butted frame tubes

According to the catalog only the following ‘531’ tubes are butted. As before, thicker butted tubes are available as Reynolds A, but H.M. is missing. The steerer is also listed here even though it is not a frame tube since it is butted. Metric sizes were also available with a 26mm diameter top tube, 28mm down tube, 28mm seat tube, and 25mm steerer.

Tube	Diameter	Length	Butt	Taper	Thick	Thin
Top	25.4	635			0.81	0.56
Down	28.6	635			0.91	0.61
Seat	28.6	635			0.81	0.56
Lady ST L	28.6		279		1.02	0.71
Lady ST H	28.6		279		1.22	0.91
Steerer	25.4	406	64	38	2.34	1.63

Reynolds ‘531’ taper gauge fork blades

I assume that the “Oval” is Reynolds “Continental Oval” (Imperial). The price list also lists the “Super Resilient” blade and options for both 1.2/0.8 and 1.2/0.9. Since it is carried over but has no catalog space, it most likely has few is any changes, but is mostly included as an option due to previous reputation. As before, there are options for doming and slotting. Fork blades were 406mm long, with a 76mm parallel section, leaving 330mm of taper and tip, a slightly longer taper than later fork blades. Note that thin thicknesses listed are options, not butts and as before S.R. is triple butted.

Tube	Diameter	Tip I/D	Thick	Thin
Round	22.2	8.9/11.4	1.42	0.91
Round	22.2	8.9/11.4	1.22	0.81/0.91
Oval	23.1 oval	8.9/11.4	1.22	0.81/0.91
D-shape	23.4 D	8.9/11.4	1.22	0.81 /0.91
S.R.	25.4		1.22→1.42	0.91

Reynolds ‘531’ plain gauge frame tubes

Plain gauge ‘531’ was available in 0.9, 0.8 and 0.7. Metric sizes were also available with a 26mm diameter top tube, 28mm down tube, 28mm seat tube, and 25mm steerer. Note that wall thicknesses listed are options, not butts.

Tube	Diameter	Length	Thickness
Top	25.4	635	0.71/0.81/0.91
Down	28.6	635	0.71/0.81/0.91
Seat	28.6	635	0.71/0.81/0.91
Head	31.8	4877	0.71/0.91

Reynolds ‘531’ seat stays

Consult the catalog direction for a listing of variations of stays. As typical, there are many options. The price list only gives 0.7 for most ‘531’ options.

Tube	Diameter	Length	Tip O/D	Thickness
1/2″	12.7	610	7.9/9.5	0.91/0.71
79/128″	15.7	610	7.9/9.5	0.71
Double Taper	12.2→14.5	variable	7.9	0.71

Reynolds ‘531’ chainstays

The catalog shows 0.8 or 0.9 in thickness, but the price list only shows 0.8 for ‘531’. As typical, there are many options.

Tube	Diameter	Tip O/D	Thickness
Chain Stay	19.1/22.2	11.1/9.5/11.4(I/D)	0.81/0.91

Reynolds ‘531’ in the 60’s

No catalog available to my knowledge.

Reynolds 531 in the 70’s

There are two catalogs available online for the 70’s. The first (alternate source) is likely 1973-1977 due to the absence of 531SL. The second is dated 1976-1980 since it predates 531Pro but includes 531SL and 753. There is one mention in a French advertisement from 1972 or 1973(?) that mentions 3/10 tubing, but this is after a trade-show Merckx prototype was shown with 3/10 tubes. It is perhaps possible that Dupieux, the Reynolds agent in France, was responsible for ordering the quantities to get 3/10 tubing drawn and distributed to French builders. However, while 3/10 tubing appears in Peugeot catalogs for custom PY10’s, it appears to only do so after the introduction of 753.

531 Frame Tubes

531 is now available in 1/7/1 in addition to the gauges it was previously available in. Previously 1/7/1 was made with “Reynolds A” hi-tensile tubing. The butting profile appears to be 280mm center, 51mm tapers, the short butt 75mm. Based on my measurements seat tubes have longer butts than 75mm. There are also the tall 531 frame tubes that are extra long added in the later catalog. The lady’s seat tubes are carried over in the first catalog but not the second.

Metric sizes were also available with a 26mm diameter top tube, 28mm down tube, 28mm seat tube 32mm x 1.0 head tube. Tubes were also available in other lengths, the longest is listed here.

Tube	Dia.	Length	Butt	Taper	Middle	Thick	Thin
Top L	25.4	635	75	51	280	0.81	0.56
Top H	25.4	635	75	51	280	1.02	0.71
Down L	28.6	650	75	51	280	0.91	0.61
Down H	28.6	650	75	51	280	1.02	0.71
Seat L	28.6	650				0.81	0.56
Seat H	28.6	650				1.02	0.71
Top T	25.4	760	127			1.02	0.71
Down T	28.6	760	127			1.02	0.71
Seat T	28.6	760	203			1.02	0.71
Head	31.7	635				0.91

531 Steerer

Threaded steerers were available in 40mm increments between 180mm and 280mm in both imperial and metric.

Type	Dia.	Length	Butt	Taper	Threads	Thick	Thin
Imperial	25.4	280	50	40	50	2.30	1.55
Metric	25.0	280	50	40	50	2.3	1.5

531 Fork Blades

Fork blades were available with various rakes, lengths, tip forms. Consult the catalog for details. Thickness is before tapering. Assuming accurate dimensions and perfect ellipses (neither of which is true), the tube diameters before ovalization can be estimated.

Reynolds “Continental Oval” (a.k.a Imperial) has a round diameter of ~22.9mm. For reference, modern Reynolds “Imperial” blades are 28.5×16.5(29×16 nominal) giving an estimated round diameter or ~22.9mm and Kaisei Imperial blades have been measured to 28.0×17.2mm giving a round diameter of of ~22.9mm.

New Continental (same as standard modern Reynolds) has a round diameter of ~23.9mm. Columbus fork blades are 28×19 giving a round diameter of ~23.7mm.

Profile	Major Dia.	Minor Dia.	Thick	Thin
Continental	28.5	16.5	1.22	0.81
New Continental	27.5	20	1.02	0.56
Track	22	22	1.42	0.91

531 Stays

Seatstays were 0.9 thick, had 380mm tapers and were available in 13mm, 14mm and 16mm with various tip forms and lengths up to 625mm. Chainstays were 0.8 thick, had 330mm tapers and were available in 22.2mm or 22mm with various tip forms and lengths up to 450mm. Consult the catalogs for more details.

Type	Diameters	Length	Taper	Thickness
Seat	12, 14, 16	625	380	0.91
Chain	22.2, 22	450	330	0.81

531 Special Lightweight/Extra Leger

While 531 had previously been sold as standard tubesets, 531SL (and 753) merited their own special designations and decals. Instead of green, the “531” on the 531SL decals was red making it easy to spot and was sold only as a complete tubeset. This tubeset featured even thinner tubes than the standard light tubes that would later be known as 531c. However, as of 1976, SL gauge tubes had “been made for some time, but were originally restricted to a few specialist manufacturers of extra-light racing bicycles.” How far this extended beyond Raleigh SBDU and in what volumes beyond team frame prototypes these tubes were supplied remains a mystery. It is possible that Reynolds was referring to French tubing which had apparently been made in similar gauges almost since the inception of 531.

The imperial version was called “Standard 850″ and the French version was called Standard 851” which had a 26mm diameter top tube, 28mm down tube, 28mm seat tube, 22mm chainstays, 32mm x 1.0mm headtube, and 25mm steerer. Fork blades were straight only. It uses the “New Continental Oval Fork” blade which might be an unraked “New Continental Oval Fork” blade that was available separately. The later iteration 531Pro seems to have used the same New Continental Oval fork blades as other 531 tubesets. There were special red decals for 531SL blades.

Tube	Diameter	Length	Thick	Thin
Top	25.4	635	0.71	0.56
Down	28.6	635	0.81	0.56
Seat	28.6	635	0.71	0.56
Head	31.7	220	0.91
Blade	27.5×20→13	397
Seatstay	16→10	600	0.56
Chainstay	22.2→11	440	0.61
Steerer	25.4	240	2.34	1.63
Bridge	12	100	0.91

Reynolds 531 in the 80’s

The following information comes from this chart (the chart is from Paterek, and not a primary source) dated to 1984 based on copyright and a video from 1982. Another brochure which is for sale has a chart which I suspect is from the 80’s based on the decals and tubesets, not the 70’s like the owner believes. Note that these sources do not entirely agree with one another. This may be due to iterative changes, or just plain inaccuracy. Following the introduction of designated tubesets in the 70’s, Reynolds released many more, some which were just mixing and matching earlier tubes. Chainstays seem to be primarily of the “chunky” round-oval-round type. 531SL was discontinued in 1981 and replaced with 531Pro so it will not be listed here. The 531 Tall tubes are carried over. This section will be organized by tubeset, not tube type.

531 Professional

This tubeset replaced 531SL in 1981. It is very similar, and the specifications in the 1984 chart for 531SL are almost the same as 1970’s 531SL. It is not entirely clear what changes were made between 531SL and 531 Professional besides different stays and fork blades(?) which sometimes bore the same green decal as other 531 blades, although red decals seem to have also been used. It may also be that the fork blades were unchanged and the information on the 1984 chart is incomplete because 531SL was discontinued by then. This example of 531Pro shows that it may have had a straight gauge steerer, however this chart says it was butted. Another chart is contradictory and says butted in one place and straight gauge in another. Supposedly it had stiffer chainstays, possibly by increasing tip diameter from 11mm to 13mm or using the ROR profile. It also had double taper seat stays as was the fashion. According to Reynolds it had 753 stays, but this chart seems to imply they are possibly different, with 753T having taper gauge stays and 531 pro having plain gauge stays. Also available in metric.

Tube	Diameter	Length	Thick	Thin
Top	25.4	600	0.71	0.56
Down	28.6	635	0.81	0.56
Seat	28.6	635	0.71	0.56
Head	31.7	220	0.91
Blade	27.5×20→13	400	1.02	0.56
Seatstay	11→16→12	555	0.56 (0.61?)
Chainstay	22.2→13	400	0.61
Steerer	25.4	240

531 Competition (531c)

Essentially giving a tubeset name to the classic set of 531 butted tubes, except with the new double taper stays and New Continetal blades. The video gives alternative specifications to the chart, but I am more inclined to believe the chart. Decal says 531c. Also available in metric.

Tube	Diameter	Length	Thick	Thin
Top	25.4	600	0.81	0.56
Down	28.6	635	0.91 (0.81?)	0.61 (0.56?)
Seat	28.6	635	0.81	0.56
Head	31.7	220	0.91
Blade	27.5×20→13	400	1.02	0.56
Seatstay	11→16→12	555	0.56
Chainstay	22.2→13	400	0.81 (0.61?)
Steerer	25.4	240

531 Special Tourist (531ST)

Not to be confused with the later “531 Super Tourist” tubeset. If the chart is to be believed 531ST only uses 1/7/1 for the downtube. The video corroborates this and highlights and mentions only the downtube as being 1/7/1. In addition to the chart, this brochure also lists the top tube as being 8/5/8. It does however feature relatively skinny 14mm single taper seat stays and heavier (thin in the video meaning Imperial oval) touring fork blades. Also available in metric.

Tube	Diameter	Length	Thick	Thin
Top	25.4	600	0.81	0.56
Down	28.6	635	1.02	0.71
Seat	28.6	635	0.81	0.56
Head	31.7	220	0.91
Blade	28.5×16.5→13	400	1.22	0.81
Seatstay	14→11	600	0.91
Chainstay	22.2→13	440	0.81
Steerer	25.4	240

531 Club Sport(531cs)

Most likely for mass production and to have a deceptively confusing name, it is not to be confused with 531c. It is a confusing hodgepodge of tubes. The front triangle of 531ST, metric(?) chainstays, and welded CrMo stays and blades borrowed from Reynolds 501. Note that the 501 decal would not be used on a 531cs frameset. Not uncommon on vintage Treks.

Tube	Diameter	Length	Thick	Thin
Top	25.4	600	0.81	0.56
Down	28.6	635	1.02	0.71
Seat	28.6	635	0.81	0.56
Head	31.7	220	0.91
Blade	27.5×20→13	400	0.91
Seatstay	14→11	600	0.91
Chainstay	22→13	400	0.91
Steerer	25.4	240

531 Speedstream

New! Oval! Aerodynamic! That picture is the extent of the official information available to me on Speedstream. 531 that was ovalized in the middle like a Huffy Aerowind. Maybe it was technically 70’s. Reynolds claims 1975. Advertisement seems to imply otherwise. It didn’t last long before getting canned.

531 SL Speedstream

A considerably lighter replacement for Speedstream, Reynolds gave up trying to fit an aero tube in a round hole. Some information can be found here. Seat stays were double taper and chainstays were ovalized.

Tube	Thick	Thin
Top	0.81	0.56
Down	1.02	0.71
Seat	0.81	0.56

Reynolds 531 in the 90’s

Some sources have dated this chart to the 70’s or 80’s, but it clearly displays post-89 decals, which is just going to be called the 90’s for convenience. 653 was a mixed tubeset with 725 (heat-treated CrMo) stays and meant to replace 531Pro. The chart only contains two tubesets named 531 with limited information.

531 Competition

Note the decal says “531 Competition” not “531c” however there appear to be no real changes. Note that italicized information is carried over and unverified.

Tube	Diameter	Length	Thick	Thin
Top	25.4	600	0.81	0.56
Down	28.6	635	0.91	0.61
Seat	28.6	635	0.81	0.56
Head	31.7	220	0.91
Blade	27.5×20→13	400	1.02	0.56
Seatstay	11→16→12	555	0.56
Chainstay	22.2→13	400	0.81
Steerer	25.4	240	2.3	1.6

531 Super Tourist

Note the decal says “531 Super Tourist” not “531ST” and the chart shows that the main triangle is full 1/7/1 tubing. While this combination was possible with tubes available before the creation of tubesets, it does not appear to be the same as “531ST” (Special Tourist). However later Reynolds literature does not seem to distinguish between the two. Chainstay has also been thickened to 0.9. Note that the 1/7 seat tube requires a 27.0 seatpost. Most of the diameters should be standard, but specifics for stays and blades and not listed.

Tube	Thick	Thin
Top	1.02	0.71
Down	1.02	0.71
Seat	1.02	0.71
Head	0.91
Blade	1.22	0.81
Seatstay	0.91
Chainstay	0.91
Steerer	2.3	1.6

531 ATB

Heavier 531 for MTBs.

531 Magnum

Oversize 531 for MTBs.

Reynolds 531 by Any Other Name

Although most frames built with 531 proudly bore the Reynolds 531 decal, there were a couple of exceptions to my knowledge. Both were the result of Raleigh USA parting with Raleigh UK. Raleigh had prior been owned by TI Group (Tube Investments) which started in 1919 as a group of seamless tube manufacturers including the bicycle tubing manufacturer A&P. (Some have claimed that their kromo, alloy formulation unknown, was air hardening, unlike typical 4130 cro-mo. However while the advertisements mention “soften[ing]” they don’t appear to explicitly mention “hardening” but instead improved strength and toughness, which can both be explained by brazing heat tempering heat treatment). Reynolds joined TI Group in 1928, and Raleigh was acquired in 1960. In 1982, Raleigh USA was sold to Huffy, who then used the brand to sell Japanese and Taiwanese bicycles alongside a few UK made Raleighs. Raleigh Technium frames, steel tubes bonded to aluminum lugs, started production f0r 1986, and then Derby acquired Raleigh USA in 1987. This technology has roots in Raleigh’s R&D when they were supplying the U.S. Olympic cycling team in 1983-84.

Raleigh 555RSL
Not to be confused with “Raleigh 555” anything else, or “Reynolds 555” (no such thing) as Huffy would have liked you to think. When Huffy acquired the rights to Raleigh USA, they decided to sell Japanese and later(?) Taiwanese made bicycles (which admittedly often had superior build quality to cheap UK made Raleighs) rather than the British cycles long associated with the British brand using British tubing. Huffy had rather cynically and somewhat deceptively badged these Japanese/Taiwanese imports with what appeared at first glance to be a British Raleigh headbadge, and Reynolds colored tubing chome-moly decal that said “Raleigh 555,” “Raleigh 555T,” or “Raleigh 555SL.” Huffy had several factors working in their favor, Raleigh had brand name recognition and did not appear to be a cheap imitator, Raleigh was British (or a least it used to be before becoming an imitator) and Raleigh began with an ‘R’ like Reynolds. It also helped that the build quality by many accounts was superior to the UK build Raleighs they replaced.

While catalogs are somewhat inconsistent, and what exactly “Raleigh 555,” “Raleigh 555T,” or “Raleigh 555SL” was changed from year to year depending from who and what they subcontacted to build bikes, “Raleigh 555RSL” and only “Raleigh 555RSL” on the higher end bikes was somewhat different. The decals said “Double butted main tubes; All tubes Manganese Moly; Manufactured for Raleigh Cycle Corporation of America by TI Reynolds; Birmingham England” and below that a decal saying “Manufactured in England.” These appear to have been actual UK Raleighs made with actual 531 throughout, but with a deliberately opaque and cynical layer of marketing. Apparently at this time Huffy thought that naming consistency was important keep up the ruse and wanted to use the UK built Raleighs to boost the prestige of their Japanese/Taiwanese imports. Later they would just decal the 531 frames with 531 decals, but keep the disingenuous “Raleigh 555” decals on the Japanese/Taiwanese bikes.

Dyna-Tech

Later both Raleigh USA and Raleigh UK found themselves under the same ownership under Derby Cycles. Raleigh USA had been producing Technium bicycles, with a steel rear triangle and aluminum main tubes glued into(onto?) steel lugs, and later steel (straight gauge 0.6mm 531 or 753 because Raleigh USA felt butting offered no benefit when not brazed) into aluminum lugs. Raleigh SPD which had been moved to Raleigh’s hometown of Nottingham also began experimenting with similar construction, building steel tubes biked glued to aluminum lugs for Laurent “Le Professeur” Fignon‘s Systeme U team. These early/prototype frames sporting Nottingham style lugs (harkening back to Nottingham made Raleigh Sports) bore normal 753 decals, not just the “753 Frame tubes” decal (possibly only used by Raleigh Techniums) found on the Raleigh USA made Techniums.

However this time it was Raleigh UK that decided to change the name and at least by 1990, Dyna-Techs bore “Dyna-Tech” decals instead of standard Reynolds decals, contrary to the Raleigh USA Techniums which bore 531 and 753 frame tubes decals despite those frames having very atypical tubes. While the Technium Reynolds 531/753 tubes were straight gauge, the Reynolds Dyna-Tech tubes were butted, which perhaps reflects different design goals. Raleigh USA wanted a stiffer frame, apparently Raleigh SPD still felt there was benefit to thinner centers and butted ends even when not brazed. It would also appear that some Dyna-Techs were sold as Techniums of US sale, and that some markets such as Germany imported both.

The stays on all titanium and manganese-molybdenum Dyna-techs may have been non-heat-treated 531 but taper gauge. It is unclear what stays were used. A 90’s catalog seems to show that 653 Record had taper-gauge chainstays, unlike standard 753 which is listed as just 0.6mm or 0.8mm for regular 653. Even though these would have been heat treated, there is no mention of heat treated stays in Dyna-tech catalogs. It maybe be that 531 stays were used because the rear triangles were brazed and not glued, although there was no prohibition against brass brazing 653 stays anywhere except the bottom bracket, which would have been a bonded joint on Dyna-techs. Note that taper gauge seat stays are very usual because the diameter is only reduced by ~25%, and taper gauge stays most likely means only chainstays.

2325 had 325 titanium main tubes, most likely straight gauge, with manganese-molybdenum taper-gauge stays and heat-treated manganese-molybdenum fork blades.

2125 was similar with titanium main tubes, with manganese-molybdenum but with no mention of taper-gauge stays or heat treated fork blades. The Technium SP1000 which appears to be a UK made product from the same time period was labeled as having 531 fork blades, titanium main tubes withed with 753.

2080 was heat treated butted manganese molybdenum steel, but 85 tons UTS, the same as later spec 753. Stays were taper-gauge but with no mention of heat treating however the fork blades were heat treated.

2070 appeared to be mostly 531 or 653 or some sort of mix, with 60 tons UTS the same as the given UTS for 653 main tubes but it also had taper-gauge stays. Fork blades were “chome-moly-manganese” which I suspect is something like a 414X series steel which has more Mn than 4130. Reynolds used “cromalloy-m” in their 501 tubeset, which was still in production, with high manganese content was claimed to retain more post brazing strength than other cro-mo and possibly explaining Reynold’s change to 520/525 when they went with 4130 (~0.3% C). The German catalog claims it is 653 main tubes with 531 stays with crmo forks.

2060 is made from chome-moly-manganese but the German catalog claims it is 531 main tubes with crmo forks. I am skeptical of the German catalog.

2055 is similar but apparently had 531 Imperial oval fork blades for better fender clearance, and I can only assume that they rank below 2060 because they are the heavy 1.2/8 fork blades instead of the lighter continental 1/5 fork blades.

Reynolds 653

Reynolds 653 was a tubeset and a member of the 531SL/531Pro family, but featured 531 main tubes with heat-treated CrMo stays or 753 stays(?) and a plain gauge steerer. Main tubes were butted to the same wall thickness as 531SL/531Pro. Specifications are similar to 531Pro, but had different material stays, shorter blades, different seatstay profile, and a plain gauge steerer (uncertain if 531Pro had this). 653 seems to have undergone at least one design revision. Some literature may point out that 653 main tubes are cold worked, but the butting process itself is cold-working. I suspect the fork blades are annealed to allow for raking which is why the strength is low. I am uncertain if Reynolds had gone to true metric at this time

Tube	Thick	Thin
Top	0.71	0.56
Down	0.81	0.56
Seat	0.71	0.56
Head	0.91
Blade	1.02	0.56
Seatstay	0.61
Chainstay	0.61
Steerer	1.545

Tube	Diameter	Length	Thick	Thin
Top	25.4	600	0.71	0.56
Down	28.6	635	0.81	0.56
Seat	28.6	635	0.71	0.56
Head	31.75	220	0.91
Blade	27.5×20→13	370	1.02	0.56
Seatstay	11→14→11	575	0.61
Chainstay	22.2→13	410	0.81
Steerer	25.4	280	1.55

Reynolds 653 Record

Reynolds also had a special lightweight version of 653 called 653 Record. I am uncertain if Reynolds had gone to true metric by this time. If the tubes were metric thickness, and 653 had 531 main tubes, then this would represent a modern iteration of a non-heat-treated 7/4/7 531 top and down tube.

Reynolds 753

There is some confusion and mystique surrounding 753 because of how rare and exclusive it was. Not only was it exclusive for the consumer, it was exclusive among producers because it required special certification from Reynolds and silver brazing to prevent ruining the heat treatment. Due to rarity and prestige there are multiple myths surrounding 753.

Reynolds 753 Myths

Reynolds 753 is a different alloy from 531
False. 753 is exactly the same alloy as 531, except heat treated. It is not a “supersteel” any more than heat-treated 4130 CrMo which can also reach similar levels of strength as 753. 753 must be silver brazed at lower temperatures than brass brazing in order to preserve the heat treatment, even though ironically superior strength after brass brazing when compared to CrMo was 531’s advantage.

Reynolds 753 is stiffer than 531
False. All steel is basically the same stiffness and density by volume. Especially so since 753 and 531 are the same alloy. Tubes of identical dimensions in either material will have identical stiffness and weight. 753 is however, stronger than 531, which means it can be drawn thinner and lighter than 531 without breaking in use. Even so, the thinnest 753 is pushing the limits. With the exception of oversize tubes, 753 main tubes are either the same or thinner and lighter, but have the same diameter as 531 main tubes, the main triangle on a 753 is either the same or more flexible than 531. Some stiffness can be gained in the rear triangle with larger diameter stays, but this only applies when the 531 equivalent is skinnier. 753 used a plain gauge steerer made from 531, which was thinner than the butted ones found with typical 531 as well.

Reynolds 753 is only 0.3mm thick
False. The thinnest 753 was drawn down to 28SWG, which Reynolds nominally called 0.3mm despite actually being much closer to 0.4mm at 0.38mm thick. Furthermore, this seems to have only been for the top tubes and seat tubes of some versions of 753. Later 753 and 753R was of similar gauge to 531SL/531Pro/653 and drawn down to 0.56mm in the thin sections. 753 may have had shorter butts because 753 specified low temperature brazing, but 531 was designed around brass brazing and being able to be hearth brazed which increases the heat affected area and calls for longer butts

753 in the 40’s

As noted in the 40’s section, the foundation for 753 dates back to the 40’s if not earlier. Note that heat-treated 531 from the 1940’s has exactly the same UTS as 1970’s 753 (although later 753 appears to have had a different/harder heat treatment that resulted in 85 tons/sq. in. UTS). However, prior to silver brazing the benefits were supposed to increase durability and make manufacturing easier rather than more difficult and delicate.

753 in the 70’s

753 was only available as a tubeset and not as individual tubes. The frame tubes were only in metric, with a choice of metric or ISO steerer and. Note that the tube lengths are all the same length, and there is no strict correlation between frame size and wall thickness, such choices were up to the discretion of the builder. 801 was ISO/heavy downtube, 802 was metric/heavy and 804 was metric/light. It would make sense that 803 was ISO/light, but is unlisted. The steerer was not butted, but instead plain gauge. A 1976 pamphlet claims the steerer was butted, which may be either an error or a design change.

Others assert 803 was thicker gauge, but I have yet to see any conclusive evidence for this. That would make the line up 801 standard/ISO, 802 standard/metric, 803 heavy/ISO, 804 extra-light/metric. An alternative explanation is that SBDU simply sometimes took a normal 531 or 531SL tube and had it heat treated considering their special relationship with Reynolds. Later 753R was very similar to 531SL but heat treated, so it would make sense they were experimenting with this. Heat treatment is relatively trivial, as tempting as it may be to attribute it to special gauges of the missing 803 set. I can not deny the possibility however that 803 was the designation for a set with gauges no thinner than 531SL/EL and it was just too shameful to sell of publish such a set that was no lighter.

The basis for 803 being a “heavy” set is oft explained by the existance of 753 frames with a seatpost larger than what was used in brass brazed frames, but smaller than 801/802/804 753. A seatpost is usually nominally 0.2mm (more often closer to 0.25mm) smaller than the ID of the seat tube. A 0.6mm seat tube results in an ID of 27.4mm, and is typically paired with a 27.2mm seatpost. However Reynolds used 0.56mm on many of their seat tubes, giving an extra 0.08mm of clearance. Normally on brass brazed frame, there is enough distortion that the same size seatpost as a 0.6mm tube is used. Silver brazing results in considerably less distortion. A metric 531EL/c seat tube would result in a ~26.88mm ID, making it fit a 26.8mm (often undersize about 0.05mm, so 26.75) seatpost with ~0.013mm clearance, or a 26.6mm seatpost as would normally be used on a brass brazed frame with seat tube distortion. A 26.8mm seatpost does not necessarily indicate an in-between size. Likewise an Imperial 531SL/c seat tube would result in a ~27.48 ID fitting a 27.4mm(27.35mm) seat post even though it would typically be used with 27.2mm. The usage of 27.4mm seatposts in Imperial 753 frames does not necessarily indicate a lighter than 531SL/c seat tube. Light reaming would give even more clearance.

If we accept the convention that light metric 753 takes a 27.0mm seatpost (~0.29mm clearance), then light imperial should take a 27.6mm seatpost, not 27.4mm. The basis for 803 being a heavier in-between set seems to but the confusing usage of 26.8mm seatposts and 27.4mm seatposts which apparently differ from the 26.6mm seatposts and 27.2mm seatposts typically used for these gauges. However, this can be explained more consistently by the fact that silver brazing results in less distortion, and Reynolds 0.56mm wall thickness is a bit of a chimera, lying almost half way between 0.5mm and 0.6mm. When distorted by brass brazing, it acts like a looser 0.6mm fit that requires less reaming. When not distorted by silver brazing, it can act like a tight 0.5mm fit.

Note that Kaisei is sold with an extremely tight fit with 0.7mm walls for a 28.6mm seat tube (~0.05mm clearance), presumably to be reamed out afterwards to change it from what would be considered a combination that does not fit to one that is merely a tight fit, like silver brazed 0.56 wall.

Tube	Diameter	Length	Thick	Thin
Top	26	620	0.71	0.38
Down L	28	620	0.71	0.46
Down H	28	620	0.81	0.56
Seat	28	620	0.71	0.38
Head	32	220	0.91
Blade	27.5×20→12	370
Seatstay	16→10	600	0.46
Chainstay	22→11	400	0.61
Steerer ISO	25.4	280	1.55
Steerer Metric	25	280	1.42
Bridge	12	100	0.91

753 in the 80’s

753 seems to have been replaced by 753R and 753T. 753T(track) seems to be slightly modified 801/802 metric-only with choice of ISO or metric steerer and double taper stays. Despite being called 753 Track, Reynolds appears to advocate its use on road for time trials, although not for rougher roads or sprints. Note that the video does not highlight frame tubes when mentioning their gauges. 753R appears to be a heat treated version of 531Pro (which did not require certification to build with), possibly with modified butting profiles based on weight differences. This chart indicates that 753T has taper gauge stays, but 753R has plain gauge stays.

753T	Diameter	Length	Thick	Thin
Top	26	635	0.71	0.38
Down	28	635	0.81	0.56
Seat	28	600	0.71	0.38
Head	32	220	0.91
Blade	27.5×20→13	370	1.0	0.56
Seatstay	11→16→12	555	0.56
Chainstay	22→13	400	0.61
Steerer ISO	25.4	280
Steerer Metric	25	280

753R was also available in metric with the standard changes.

753R	Diameter	Length	Thick	Thin
Top	25.4	600	0.71	0.56
Down	28.6	635	0.81	0.56
Seat	28.6	635	0.71	0.56
Head	31.7	220	0.91
Blade	27.5×20→13	370	1.02	0.56
Seatstay	11→16→12	555	0.56
Chainstay	22.2→13	400	0.61
Steerer	25.4	280

753 in the 90’s

What was previously known as 753R in the 80’s seems to have simply become 753 in the 90’s with little change except for a change in stays again. However Reynolds may have gone to true metric by this point in time. Reynolds apparently also apparently changed the heat treatment resulting in 85 tons/sq. in. UTS although they also seem to have changed the way they measured as they now counted butted main tubes as cold worked. There was also an oversize version with a larger top tube and downtube.

Tube	Diameter	Length	Thick	Thin
Top	25.4	600	0.71	0.56
Down	28.6	635	0.81	0.56
Seat	28.6	635	0.71	0.56
Head	31.75	220	0.91
Blade	27.5×20→13	370	1.02	0.56
Seatstay	11→14→11	575	0.61
Chainstay	22.2→12	410	0.61
Steerer	25.4	280	1.55

The 753 Conspiracy Theory

The Custom Bicycle (p. 98) gives an account of the development of 753 by Tube Investments, who both made Reynolds tubing (1928) and produced Raleigh bicycles (1960). Gerald O’Donovan headed the new Ilkeston factory (a.k.a. SBDU) and after experimenting with titanium and seeing the shortcomings, worked with Reynolds who “discovered an interesting tube, but they didn’t know what to do with it.” It is curious phrasing, how exactly does one discover a tube? Bicycling claims it was developed for rocket casings. Is it possible that when Gerald O’Donovan asked for a lighter stronger tube, Stan Smith and Terry Reynolds went back in the Reynolds archive to find the heat treat recipe that Reynolds used in the 40’s? Reynolds 753 is the same alloy as 531, the only difference is the heat treatment, which has existed since the 40’s. In the early experimental stages is it possible they used Dupieux’s rumored 3/10 metric tooling, explaining why the early tubes were metric, which some claim also date back to the 40’s or earlier? The use of metric and thinner tubes is an off choice when O’Donovan is said to have quit titanium due in part to non-standard diameters and a proponent of the use of oversize thinwall tubes. The key to 753 may lie in the question posed in the story, “How do we join it?” The use of silver brazing preserves the heat treatment of 753, but also makes it hard to overheat and damage the thin steel tubes, which is why many builders used silver even on 531SL.

Reynolds 531 oddities

French Tubes
French versions of tubes came in metric diameters, 28mm (vs 28.6mm) downtube/seattube, 26mm (vs 25.4mm) toptube 22mm (vs 22.2mm) chainstays and 32mm (vs 31.7mm) headtubes. France being proud of the metric system were no doubt proud they could make perfidious Albion make tubes in metric measurements. The British on the the hand were no doubt proud that the French recognized British Reynolds tubing as the finest cycle tubing and preferred over their much cheaper domestic Vitus tubing.

If Daniel Rebour can be trusted then the French had very different tubes available compared to the Anglosphere. 7/3/7 (most likely 0.38mm) speciale, 7/5/7 (most likely 0.56mm) course and 1/7/1 standard and claims that non-French simply do not know what they are talking about. This is somewhat supported by a 1972/73 french advertisement mentioning 3/10 mes tubes, but also somewhat invalidated by the fact that Rebour’s point of dispute was that 3/10 tubes predated the 1970 Merckx (featured at the Reynolds stand) R&D/show bike and the 1972/73 advertisement may simply be referencing the show bike as it also mentions Merckx at the top.

The only mention of 3/10 tubes I can find in mainstream French catalogs are after 753 was introduced. Mentions of 5/10 and 7/10 tubes can be found, but the 5/10 measurement may simply be referencing the thinnest tube, the top tube as Reynolds sometimes liked to do. Even though this 3/10, 5/10, 7/10 system seems to match Rebour’s understanding of French Reynolds tubing, except for his claim of 3/10 tubes predating 1970, it can also be explained just as easily by Reynolds’ marketing practices.

Cantiflex
An early attempt to fit oversize tubes in standard sized lugs. This was done by tapering both ends of the tubes so the diameter was greater in the middle, but the right size to fit lugs. These had their own unique 531 decal.

Schwinn Paramount
Around 1979 when The Custom Bicycle was published Frank Brilando, Schwinn VP in charge of engineering stated that Paramounts did not use normal 531. Brilando placed great importance on rigidity (he’s been seen posed next to a 23″ Varsity, he could have been more in the ~60cm frame range, where frame rigidity is a problem) and strength but little emphasis in lightness (Paramounts were Schwinns after all). He would also substitute straight gauge 4130 on extra large frames for the downtube and seat tube. For the time period, Paramount’s 531 was a 1/7/1 DT, 1.2/8/1.2 TT (according to the book that’s how it was, perhaps because the TT is the most flexible tube with standard lugs, or because top tubes tend to get dented), 1.2/9 extra stiff chainstays and 1.4/9 (Reynolds track gauge) fork blades. Bilando states this to be the standard 531 Paramount used at the time, used for all the standard track and road frames, but being based on his or Schwinn’s ideas on how to make a bike, these extra thick gauges represent the exception rather than the rule.

Raleigh (USA) Technium
Having felt that they had not gone far enough gluing aluminum tubes into an otherwise steel frame, Raleigh USA decided to glue steel tubes to aluminum lugs (coefficient of expansion be damned) to improve stiffness (yes, steel which is inherently stiffer, to increase stiffness). Unlike Raleigh across the pond, Raleigh USA felt that butting was unnecessary without the heat of brazing, but they also opted for relatively thick straight gauge 0.6mm tubes for both 753 and 531 with a standard top tube and half-oversize (1 3/16, half way between 1 1/8 standard and 1 1/4 oversize) down tube and seat tube for a claimed 20% increase in stiffness over their aluminum models. The 753 frame weighed the same, it was just less likely to get dented or bend if you thought the 0.6mm wall thickness wasn’t enough and you were more concerned about the tube failing rather than the joints. Stays were True-Temper, not Reynolds, and the frames proudly bore 531 and 753 “Frame Tubes” decals for their 3 straight gauge 0.6mm thick tubes, which were otherwise the same except for heat treatment. Another point of difference from Raleigh across the pond.

Raleigh (UK) Dyna-Tech
When SBDU dabbled in bonded steel frames, they didn’t feel the same as Raleigh across the pond. They built glued steel frames with butted 753 and 653/531(?) tubing but called the tubing Dyna-Tech even though the tubing was made by Reynolds, seemed to have been 753/653/531 and Raleigh USA had no compunctions about using 753/531 nomenclature and use of 753 decals on prototypes. It is unknown whether they thought 753 didn’t sound modern enough and 2080 sounded more technical and it justified a special name due to not being weakened by brazing, or if they didn’t want to besmirch their 753 brazed frames with glued frames. Read more in the Dyna-Tech section of Reynolds by any other name.

Thorn
A fairly prominent maker of modern steel touring bikes that used a custom mix of Reynolds. In case there was any confusion about what tubes they used, inspect their tubing decal.

The End

Reynolds eventually discontinued the once dominant 531 and 531 derived tubesets as the market shifted away from lugged steel frames. While there exist some 531 welded frames, 531 exhibited relatively poor weldability (manganese has a low boiling point and vaporizes at welding temperature, producing toxic fumes, neither good for the welder nor weldee), and only offered appreciable advantage when brass brazed. I suspect 753 offered little advantage over heat-treated CrMo, and Reynolds seems to agree. Given the shift away from lugged steel to welded steel and alternative frame materials, Reynolds branched into titanium, aluminum and carbon (Ouzo forks) and focused on weldable steel. 531 was replaced with the weldable CrMo Reynolds once deemed inferior. 753 was replaced with air-hardening 853 which is even stronger and gets even harder when welded (still plenty strong without welding, but silver brazing does not heat up the tubes enough for this). Note that Reynolds 653/853 should be brass brazed (in excess of 850C or 1560F) in order to take advantage of the air hardening, as silver brazing will not heat the tubes enough to get a hardening response. The lower heat of silver brazing will merely temper the heat treatment softening the steel. Reynolds released a limited edition 531 tubeset, and still makes 531 tubing for large special orders. Pashley uses 531 on many of their frames and 531 main tubes are available from Strawberry Cycles.

NOS 531 Measurements and Framebuilder Info

If you have a affordably priced NOS 531SL, 531EL, 531 metric, or 753 tubeset, please contact me so I can add more measurements.

I was able to procure a NOS 531 (531c type, but estimated to be 60’s or 70’s vintage) tubeset and NOS “Continental Oval” (Imperial) and “New Continental Oval” fork blades. The following are actual measurements. This tubeset is representative of typical double butted 531 and mixes different gauge tubes unlike most modern tubesets. Note that some production frames have utilized extra light tubes like 531SL/Pro and others have utilized thicker tubes like 531ST. Listed are similar tubes commonly available in the U.S.

Note that heat-treated 4130 like Reynolds 725, Vari-Wall Chromoly CMH, and Kaisei tubing should either be silver brazed at low temperature like 753 in order to preserve the heat treatment, or welded to minimize HAZ and preserve the heat treatment in the rest of the tube.

Air-hardening steels like Reynolds 853 and 631 require high heat to air-harden and should be welded or brass brazed to take advantage of the air-hardening effect. If silver brazed, 853 will respond like heat-treated 4130 so care should be taken not to damage the heat treatment. The lower temperature of silver brazing will only temper the heat treatment and soften and weaken the tube rather than getting a hardening response, although 853/631 are still stronger than heat-treated and non-heat-treated 4130 respectively. Builders to silver braze these frames may argue that brass brazing or welding will result in a part of the tube that was high enough to ruin the heat treatment but not high enough to harden the steel, and they would not be incorrect. However Reynolds used to advise against silver brazing 853 and that brazing should be above 850C. On the plus side, this means 853 is ideal for fillet brazing, as it will not be damaged by brass brazing temperatures, and is resistant to being cut by the file after hardening.

Regular 4130 and similar steels maybe be joined with either silver or brass. Silver will be easier on the tubes, but countless frames have been made with brass without problem. While many builders feel brass is more forgiving to build with, silver is easier on the tubes and makes it harder to accidentally overheat thin wall tubes.

Seat Tube

Gauge	Diameter	Length	Weight
21/24	28.6	635	280

Corresponds to calculated weight for ~175mm butt (280g). This seems reasonable, modern 531 has a butt of 180mm and sliding some 27.2mm seat tube down the tube indicated the butt is signifigantly longer than 75mm. Similar tubing is available in Reynolds 531, 631 and Columbus SL, Spirit, Zona, Dedacciai Zero, and Zero Uno. Reynolds 631 with 0.55mm walls is the closest.

Top Tube

Gauge	Diameter	Length	Weight
21/24	25.4	635	256

Slightly lighter than calculated (263g, -2.7%), but not light enough to be a true 8/5/8 tube with 280mm center. Weight corresponds with ~325mm center but could just as easily be explained with manufacturing variance. Similar tubing is available in Reynolds 531, 631, Columbus SL, Zona, Dedacciai Zero Uno and Nova Crmo. Tubes with 0.6mm centers like Zona and Dedacciai Zero Uno tubes with short centers like Reynolds 531 and Nova Crmo will be the closest.

Down Tube

Gauge	Diameter	Length	Weight
20/23	28.6	635	335

Slightly heavier than calculated (328g, +2.1%). Weight corresponds with ~245mm center but could just as easily be explained with manufacturing variance. Similar tubing is available in Reynolds 631 (sold as a top tube), Columbus Cromor and Nova Crmo.

Head Tube

Gauge	Diameter	Length	Weight
20	31.75	190	146

Heavier than calculated (132g, +10.6%), corresponding to 1mm wall. Similar tubing is available in Reynolds 525, 725, 853, 921, Columbus SL, Chromor and Nova Crmo.

Steerer

Gauge	Diameter	Length	Weight
16/13	25.4	220	218

Lighter than calculated (236g, -7.6%), although some material was removed for threading. It does not come with a keyway for headset washers. Similar tubing is available in Reynolds and Nova Crmo.

Seatstays

Gauge	Diameter	Length	Weight
20	16→10	625	209/213

Weighed approximately the same as calculated (212g, -1.4%, +0.5%). Stays are not pre-butted. There particular ones seem to be 0.91mm thick. 531 was paired with a large variety of stays as noted above.

Chainstays

Gauge	Diameter	Length	Weight
21	22.2→12	440	176/180

Lighter than calculated (188g, -6.4%, -4.3%). Stays are not pre-butted, unlike many modern options. Tubes are no longer available fluted to tire and chainring clearance, but round and round-oval-round is available. Most alternatives only have 290mm long tapers. Similar tubing is available in Columbus Cromor, Kaisei and Nova Crmo.

New Continental Oval Fork Blade

Gauge	Diameter	Length	Weight
19/24	27.5×20→12	372 c-c	153/154

Lighter than estimated weight (162g, -5.6%, -4.9%). Circumference is ~75mm giving a diameter of ~23.9mm. Wall thickness was ~1.0mm at both ends. Taper is ~330mm. This corresponds with calculations that expect wall thickness to increase in the same proportion diameter decreases. Similar tubing is available in Reynolds Crmo, 631 and 853. Other alternatives are Columbus SL and Nova Crmo. However modern fork blades tend to be Columbus pattern and also have short tapers.

Continental Oval (Imperial) Fork Blade

Gauge	Diameter	Length	Weight
18/21	28.5×16.5→12	398 c-c	212/212

Lighter than estimated weight (225g, -5.7%). Too heavy to be 1.0/0.5. Circumference is ~72mm giving a diameter of ~22.9mm. Wall thickness was ~1.3mm at the crown, and ~1.6mm at the tip. This corresponds with calculations that expect wall thickness to increase in the same proportion diameter decreases. Taper is ~330mm. Note that the diameter is different from “New Continental” and modern fork blades. Reynolds makes a similar “Imperial Oval” fork blade. Kaisei “Toei Special” fork blades are not the same and significantly thinner walled, most likely ~1.0mm even thickness pre-butted. However modern fork blades tend to be Columbus pattern and also have short tapers.

The French 3/10 Mystery and Other Metric Madness

Many secondary and tertiary sources mention 3/10 Reynolds 531. If anyone has any French Reynolds catalogs, prices lists or correspondences with Dupieux please feel free to contact me.

The evidence in chronological order:

REYNOLDS H. M. 1936
Their new composition of steel assures you a quality unmatched
For Your Guarantee – For Your Safety
Demand your frame be REYNOLDS H. M. throughout
with the decals of guarantee on a yellow background

yellow background
BUILT WITH 3 TUBES BUTTED
CHAINSTAYS SEATSTAYS
REYNOLDS H. M.

yellow background
REYNOLDS
FORKS
REINFORCED
H.M

REYNOLDS
FORKS
REINFORCED
S.R.

blue background
BUILT WITH 3 TUBES BUTTED
REYNOLDS H. M.

Light road series 1340
5/10 with 7/10 butts. Weight 770g.

Normal road series 1342
5/10 with 9/10 butts. Weight 815g.

Special extra-light series 3/10 with 6/10 butts weight 600g.

1935 is the year 531 was introduced, but also where Reynolds first mentions Dupieux in their history. It is noteworthy that this is an advertisement in 1936 showing H.M. as the premium steel not 531. The listed gauges lend credence to the idea that France had their own unique gauges based on what Dupieux ordered since metric tubes would need their own dedicated tooling anyways. However the mentioned gauges different from the 3/10, 5/10, 7/10 hierarchy often given from French Reynolds. Weights appear to correspond with the 3 main tubes. Seatstays and fork blades would have likely been identical to their British counterparts, chainstays were possibly “close enough” requiring bottom bracket shells to be filed to fit an extra 0.2mm of diameter. These are all lighter than the 531C type tubeset in Imperial sizes that dates back to at least the 40s.

There are also some mentions in various publications of a Barra made frame with this 3/10 H.M. tubing as a publicity stunt in trying to make an ultralight bicycle.

I am unsure how the weights are determined. Lengths and butts are unknown, Reynolds typically made tubes to 600mm or 635mm uncut, but has also shown “typical” weights of cut tubes for a medium size frame.

The following is an excerpt from l’Officiel de l’automobile du cycle de la motocyclette circa 1937:

The bicycle frame, because rigidity and robustness are essential, has been the subject of incessant research from the first tubes of long ago to those of today.
Now, a solution has just been revealed, from investigations and progress in British metallurgy, which gives the frame increased strength. This innovation is applied in no better place than the fabrication of ultra-light cycles, fully the order of the day, because the metal can be cold or hot without modification of its physical properties.
This solution is particularly suitable for autogenous construction.
This is the tube Reynolds calls “H.M. 531,” a designation which corresponds to a formula from the research laboratory of the large Birmingham firm.
Before being launched on the market, this rube was subjected to severe and prolonged trials.
We will give a precise idea of of the static tests in the table below, a comparison between three different materials.

-Reynolds A.
-H.M.
-H.M. 531

Material – Elastic Limit [similar to yield strength?] – Breaking Load [similar to tensile strength?] – Brinell Hardness (units in kgf/mm^2)
Reynolds A – 55 – 63 -187
H.M. – 63 – 70 – 207
H.M. 531 – 70 – 78 – 228

Additionally, “fatigue tests” also highlight the “endurance” of “H.M. 531,” while deformation for Reynolds A occurs at 32,400 reversals in a scientifically prepared experiment, it occurs for H.M. after 67,500 reversals and for “H.M. 531” after 162,100 reversals, which represents an increased strength of 100%.

On the other hand, note that the micrographic test after brazing shows the metal of “H.M. 531” retains fine grain structure as well as all of its physical strength properties.

For the French market, the tube is delivered – by M. Dupieux, who is the exclusive agent for Reynolds – with models:

– extra light 5/10 with 7/10 butts in 22/24
– light 5/10 with 9/10 butts in 20/24

This new tube is not without already having a brilliant track record: it equipped the machines of the winners of the great events of 1936: Paris-Roubaix, Bordeaux-Paris, French Championship, World Championship, etc.

This except would make it appear as though 531 entered the French market early 1937. Much of the technical data mirrors those from English sources.

The mentions of 7/5/7 and 9/5/9 tubes would indicate that the gauges from 1936 are not a typo. It would seem that Dupieux requested the thinnest centers Reynolds felt comfortable with, with either 9/10 butts which were easier to braze, or 7/10 butts which were slightly lighter, less than a 45g difference based on the H.M. weights. 7/10 would be more flexible than 9/10, but the flexibility would be mostly determined by the centers which have the lowest K values. Modern production 8/5/8 531 would make a good approximation of either of these French 30’s 531 tubesets for those who idolize the 30’s randonneuse.

Usage of SWG gauges is also noteworthy. It confirms that metric tubes were made in SWG wall thicknesses, just like later metric 753, as well as confirming that 9/5/9 does not appear to be a typo despite the apparent 4/10 difference between butt and center. Indeed there are frames of the era with “REYNOLDS BUTTED 20-24” markings. Note that 24 gauge is actually 0.56mm, meaning the difference is only 0.35mm, and that there were occasionally tubes that had a greater than 0.3mm difference. These gauges do not seem to correspond with Imperial tubes of the 40s, although I don’t have much technical 531 data from the 30’s Anglosphere side of things. The use of SWG here, and the corresponding fractional mm used would also indicate to me that 6/3/6 H.M. tubes were in fact 0.61/0.38/0.61, similar to some modern production 853 tubes.

There is a distinct lack of a 3/10 531 tube, despite the apparent prestige gained by advertising 3/10 H.M. tubes in 1936. 7/5/7 had been upgraded to “extra-leger” status from merely “leger,” and 9/5/9 to “leger” from “normal.” It seems to me unlikely that Dupieux would neglect to show off 3/10 531 tubes if he had them. Perhaps Dupieux was sitting on old 3/10 H.M. stock. Most likely these tubes were only used in special racing applications, show bikes, event specific bikes, or for picky customers. It seems to me that these were indeed “speciale” purpose and did not find their way onto most machines. Only one year later, and Dupieux did not find it urgent to refresh his stocks of 3/10 with new and improved 531, but did feel compelled to order 5/10 tubes both in 9/5/9 and 7/5/7, which were likely the tubes finding their way onto most high quality French bikes of the era despite being no lighter than the H.M. tubes. Apparently 7/5/7 and 9/5/9 was what was actually selling and being used. 3/10 would appear to be more of a publicity stunt or for special applications where grams were being counted.

There seems to be a misconception that 3/10 tubes were strong, practical and commonly found on the high quality bikes of the era. While I have no strong evidence, most circumstantial evidence seems to show 3/10 tubing being a rarity and mostly used on event-specific bikes or for customers that wanted the lightest possible frame. Concours de Machines (Technical Trials) may have had fenders and some luggage, but were far from practical or durable despite the rigors of the course. They were used to advertise the pinnacle of cycle manufacture in France, much the way modern bikes are used in the pro peloton. People who complain about “impractical” and “disposable” bikes today should take a close look at Concours de Machines bikes for an exercise in futility.

Using Rene Herse as an example, you had practices like making low rider front racks with no handlebar bag, the sole reason people have nowadays in commissioning a randonneuse, in turn making the cargo inaccessible, just because the rack would be lighter, or removing the part of the crank with extractor threads just to shave a few grams during weigh-in, making the bike not serviceable with standard tools. Riders were disqualified because of equipment failure, because components were being made as light as possible to just survive until the end of the event, hopefully. But with victory came prestige, the astonishing (tireless) weights showing off skill in fabrication and invaluable marketing.

Given most documented uses of 3/10 tubing, I see no reason it was any different. A way to shave every last gram on an event bike designed to survive an event instead of long term durability, or having enough rigidity for general usage. Had 3/10 been in common usage on machines meant to be durable, the increased strength and fatigue resistance of 531 would have been much appreciated.

Translation coming soon…

I found this advertisement in L’Auto, of Tour De France fame. Basically is says 5/3/5 (0.56/0.38/0.56) and 7/5/7 (0.71/0.56/0.71) tubes. 3/10 is back to being extra-leger and 5/10 is back to merely being leger. Don’t ask me why the switch.

Roger Riviere’s hour record bike circa 1957. You can see the extra legers 3/10 on the sign. Eddy wasn’t the first to set the hour record on a bike made from 3/10 Reynolds 531.

TUBES AND FITTINGS
⚫ REYNOLDS, in its new stand, without doubt the most elegant of the Show, presented as an example, a very beautiful frame in lime white, tubes 3/10, and a frame of Eddy Merckx.
The three classic series were exhibited, tubes in 7/10 with 10/10 butts (the seat tube being 5/10 with an 8/10 butt) 5/10 with 7/10 butts, and 3/10 with 7/10 butts.
Note that, more and more, we demand seatstays of 16mm and chainstays of 22.
Here are the weights of the complete series:
7/10 = 2.400 kg
5/10 = 2.100 kg
3/10 = 1.700 kg
Certain foreign representative who directly asked REYNOLDS (England) for the 3/10 series was told that the lightest was in 4/10; also this visitor told us there was no 3/10. But he was ignorant that this model of tube is one exclusive to Ets DUPIEUX France, fabricated at his request, and that the French importer is the only one in the world that can supply the series of REYNOLDS in 3/10.

Francophile cyclists should recognize the name Daniel Rebour. Rebour makes some interesting claims in this article, although they are nearly impossible to verify. Rebour seems to be claiming that the French had access to a completely different line of tubing than the rest of the world. 7/10 seems to roughly correspond with 531ST (2300g) except with a heavier top tube. 5/10 seems to roughly correspond with 531C (2050g) but with heavier fork blades. It really should be closer to 531SL/Pro with some allowances made for heavier stays. 3/10 is optimistically listed as lighter than 753T (1750g). Rebour lists different weights in his book (2.445 kg, 2.145 kg and 1.795 kg respectively) . 1970’s catalogs unusually show many customization options for stays, but no options for wall thickness. The 1950’s catalog offers two options, but none as light as the lightweight stays found in 753 or 531SL/Pro. The 3/10 tubes offered in 1970 according to Rebour seem to be different than the ones offered in the 30’s. 9/5/9 has been replaced with 1/7/1 (with 8/5 seat tube) and 6/3/6 replaced with 7/3/7. If there were 0.71/0.38/0.71 531 tubes out there, it might explain why early 753 was metric.

This is one of the only mentions of 3/10 531 I have seen. Advertisements both before and after often show 5/10 mes, but neglect to show 7/10 mes or 3/10 mes. Other sources however, such as French bicycle catalogs do show both 7/10 and 5/10 variants. This advertisement was also incidentally published when Merckx attempted the Hour, and said to be riding on 7/3/7 tubes. If 3/10 tubing was a standard option as Rebour insists, why does it not show up in other 531 advertisements that apparently only show 5/10? Here, like in 1936, the 3/10 tubing seems to be adding brand prestige, but if it was readily available, it would be expected that 3/10 be advertised instead of or in addition to 5/10.

From Rebour’s book Cycles De Competition Et Randonneuses circa 1975. It provides similar but more detailed information than his article about the Salon de Paris and gives alternative names to the series. After this point 3/10 531 becomes more or less irrelevant as 753 is introduced. Also worth noting is the introduction of 531SL which roughly corresponds with the 7/5/7 tubing. Some French sources have claimed French 531SL is merely their traditional 5/10 mes 7/5/7 tubing, but with a new red decal, however these sources often imply that a green decal means 7/10. French advertisements after the introduction of 753 and 531SL seem to no longer mention wall thickness. However, some sources feel that 753, 531SL and 531 correspond with “traditional” French 3/10, 5/10 and 7/10 although I find the given wall thicknesses extremely dubious.

The Custom Bicycle mentions that Peugeot uses 0.3mm 531 tubes, but this may be in error, and it may be 753, as both the book and catalog mentions of 3/10 tubing are after 753 was introduced.

It seems to be complaining about the ridiculousness and the wisdom of 6/4/6 tubes in the smallest frames

The Competition

Reynolds has had many competitors over the years, including but not limited to Columbus (Italian), Vitus(French), Tange(Japanese) and Ishitawa(Japanese). These were almost all cr-mo similar to 4130. There was Mangaloy, but this was less alloyed and a different composition than 531. I will not explore all tubesets here, but will include the more common and iconic tubesets.

Extra-light Tubesets

While 753 is one of the most famous ultralight tubesets, because of the inaccurately described 0.3mm(0.38mm) wall thickness, silver brazing requirement, and the certification process, other tubing manufacturers did produce similarly light tubesets. Columbus historically did not believe in tubes lighter than 0.5mm, so their lightest tubeset was 0.5mm straight gauge Columbus Record tubeset used on many hour attempts. They also had a 7/5/7 KL tubeset. Vitus is somewhat infamous for their flexible and skinny aluminum tubeset called 979, which is a common sight on Alan type lugged aluminum frames. Tange had 7/4/7 Prestige and also a 6/3/6 Champion Pro version. Ishitawa has a 7/4/7 tubeset called 017, and an even lighter one called 015.

8/5/8 Tubesets

More or less comparable to 531SL/Pro, these include Columbus Brain (and current SL), Vitus 980, Tange Champion No.1 and Ishitawa 019.

9/6/9 Tubesets

Instead of the lighter top tube of 531C type tubesets, the competition tended to produce 9/6/9 tubesets, although lighter tubes were often available to those that wished to use them. These include Columbus SL, Super Vitus 971, Tange Champion No.2 and Ishitawa 022.

1/7/1 Tubesets

Comparable to heavier 531, comparable tubesets are Columbus SP, Vitus 171, Tange and Ishitawa 024.