Clutched (One-way) Shifters

If you ask someone about a clutch on a bike, they will probably have no idea what you’re talking about, think you mean the clutch on a motorbike, or they might think you’re talking about these newfangled rear derailers that keep the chain from coming off. If you ask someone what a clutched rear derailer does, some will answer that it just has a really tight chain tension spring, others might say it allows the cage to move freely in one direction, but adds resistance in the other. This is hardly the only place a one-way clutch was ever used on a bicycle. The freewheel and freehub also use one way ratchet (rarely roller) clutches to allow coasting. Sachs who is credited with inventing the bicycle freewheel referred to the mechanism as a clutch over 100 years ago.

There were also a special category of friction shifters that used clutches to allow free “frictionless” rotation in one direction, but provided friction in the other direction to resist the cable tension of the derailer return spring. This allowed signifigantly reduced effort when pulling on the cable to downshift. With a friction shifter the friction must be high enough that it can resist the derailer’s return spring force and not slip. When upshifting effort is friction minus spring force. When downshifting, effort is friction plus spring force. This means the effort to downshift can be many times the effort to upshift as the upshift effort may be very low if the friction is barely more than the spring force, but effort to downshift is at least twice the spring force. With a clutched shifter, the effort to downshift is just the spring force because the clutch bypasses the friction element. This means force to downshift and upshift are considerably more balanced, making it easier to shift and trim. There’s also the benefit that the anti-rotation washers tend to only rotate in one direction, against the boss flats or square, so they’re less likely to come loose unlike with normal anti rotation washer which tend to wiggle in both directions during use.


Suntour’s famous “Power Shifters,” made even more famous by their barcons. The lever ratchets freely around the spur wheel in one direction, but locks against it in the other direction allowing the friction of the spur gear to resist the spring force of the derailer. It clicks when downshifting, but is smooth when upshifting. Invented by Nobuo Ozaki who invented “safety” levers for Dia-Compe, and according to some, the slant parallelogram derailer (although Testuo Maeda appears on patent forms). Appears to have first been produced in 1971 for leisure/touring bikes as either stem shifters or barcons. One version even has an integrated bell mount. They appeared shortly after as downtube shifters and thumbies. Later higher end versions meant for Suntour’s better groups had even finer ratchet teeth.

Priority: 1970-11-26
Publication: 1972-09-26
Earliest known production: 1971

Patent drawing
1983 Suntour small parts catalog
April 1971 advertisement
June 1971 advertisement
1973 Suntour Catalog (edited)


Shimano felt forced to respond and came up with their own convoluted and more difficult to manufacture patent dodging solution. Instead of a simple spur wheel and spring pawl, the Shimano version used a star ratchet system with one half as the friction element, the other half splined to mate with the lever but allow movement for the ratchet system to work, and a separate coil spring. Not enough ratchet teeth. The coarse teeth lead to low precision and clunky feel. It came hooded or unhooded depending on the specific model, and on top tube, downtube or stem mounts. The design was changed slightly in later years. A drawing from a following patent has been included because it shows a clearer cutaway. Incredibly hard to find the patent because it seems to have been in Japan only.

Priority: 1971-08-05
Publication: 1973-03-30
Earliest Known Production: 1972

Drawing from first patent (left) and drawing from second patent (right)
1973 Shimano parts catalog (edited)
1972 Shimano catalog (edited)
1975 Shimano catalog


Not content to merely imitate Suntour with a costlier, more complex and clunky solution, Shimano came up with a cheaper, simpler and smoother solution by implementing a spring clutch wrapped around a simple bushing which acted as the friction element. It did not require machining teeth into the spur gear and abandoning the ratcheting design meant a smooth action with no clicks in either direction. It was never produced in a braze-on model, only various clamp on models and Schwinn’s headset washer mount. Oddly enough many of the small parts and the barrel size of the levers themselves vary between some mounts. Even though Shimano’s application date was in 1972, they do not seem to have been produced until 1974. It does not show up in catalogs until 1975 but it is not shown as a new product there, and it graced many a 1974 Schwinn Le Tours (first model year) as stock equipment and was commonly paired with early Shimano 600. The coffin shaped hoods were later changed to less offensive and more retro, even at the time, rounded ones. Road versions seem to have quietly disappeared around 1980 or so as Shimano revamped their product line to have clear hierarchies with their new and radical AX components. This left little room for unusual non-series components like Unishift, but it reemerged in pre-index Deore XT thumbies which competed with Suntour thumbies on early MTBs. The French patent number has conveniently been included for reasons.

US3886806A (FR2193735A1)
Priority: 1972-07-20 (FR Application: 1973-07-19)
Publication: 1975-06-03 (FR: 1974-02-22)
Earliest Known Production: 1974

Patent drawings
1975 Shimano catalog
1975 Shimano catalog
1978 Shimano catalog
1984 Shimano catalog


Simplex loses the priority date by a several months to Shimano, but could have been independently invented by Juy and the Simplex units seem to have made it to market faster than Shimano’s. Some have claimed 1972 as the date of introduction, but it does not appear in the 1972 catalog supplement where SLJ first appears. Most likely this date was arrived at because the SLJ group was introduced in 1972 but offered with normal friction shifters at the time. It definitely shows up in the 1974 catalog, but is not yet branded SLJ. Initially offered in band on models, versions for Simplex braze-ons and Campagnolo (standard) braze-ons were later produced. A later patent on improvements show the purpose for the mysterious nub, despite never actually being fully implemented. It’s interesting to note that while Shimano’s Unishift faded from road, Retrofrictions gained prestige for Simplex by being popular replacements for even Campagnolo in the pro peloton. For a company hoping to reinvent itself as a purveyor of top quality drivetrain components after almost two decades of being known for making cheap plastic bike boom junk, there was no better endorsement. Of course Lucien Juy could not resist making them in plastic as well. Simplex went on to eventually produce versions for Spidel (a group made of several component manufacturers), Gipiemme, and Mavic. A later Mavic design seems to have been produced by Simplex as Simplex had some similarly shaped levers, and Mavic seemed to be selling rebadged and slightly customized Simplex derailers.

GB1455707A (FR2210169A5)
Priority: 1972-12-12
Publication: 1976-11-17 (1974-07-05)
First Known Production: 1973(?)/1974

Patent drawing
Patent drawing for a modification to allow adjustable overshift, like Shimano Deore Centeron (1974)
1979 Simplex parts catalog
1974 Simplex catalog
1977 Simplex Catalog
1981 Simplex catalog
Mavic 1990 Catalog


Although often derided as merely a patent dodging knockoff, Huret offers an interesting take on the spring clutch because it’s not really a one-way clutch, it’s a two-way clutch. The spring clutch is tightened by the cable tension as normal, but Huret’s spring clutch has two tabs to loosen it instead of just one. When downshifting, it works the same as Unishift/Retrofriction and loosens the clutch in that direction. When upshifting, instead of the clutch locking to a friction element, the lever loosens the clutch but in the opposite direction. It reduces the friction of the clutch shifting in either direction with the lever rather than overcoming the friction of the friction element when upshifting. This means there should be no need to adjust the friction to match the spring tension on the cable and limits ghost shifting as tension on the cable increases the friction. Normal one-way shifters must still have the friction adjusted to resist the cable tension of the derailer spring. The downside to this is that the cable must wrap around a sleeve that moves with the spring because otherwise it would have to slide in the cable groove and it can not be tuned to offer roughly equal resistance in both directions. What makes it “ratchet” is not that it actually uses a ratchet, but that there is a toothed non-rotating spur wheel that seems to have no purpose but provide detents for microindexing for tactile feedback. It seems easy enough to remove if you want smooth action like Unishift or Retroshift, but pragmatically microindexing makes it a touch easier to trim even if it does not seem as refined. That’s in theory at least. In practice, there’s a bit too much slop in the mechanism so that the lever can have a neutral position where it is not applying force to either tail, and the detents serve to prevent the lever from flopping around loosely. This is not an issue in other designs because there is always tension on the lever body in other designs. It was available as downtube, toptube and stem clamp-on models but not braze-on. However it is possible to mount braze-on shifters to normal Huret downtube shifter bands with the right screw, so the reverse may be possible.

Priority: 1974-11-22
Publication: 1976-06-18
Earliest Known Production: 1976

Patent drawing
1978 Huret catalog (edited)
1978 Huret catalog (edited)


An unpleasant shifter, the lever was inelegant and chunky, the internals were made of plastic with coarse teeth, something you could even feel while shifting as they lacked the precise crisp clicks of Suntour’s Power Shifters. Instead of a pawl, there was a multi-toothed plunger driven by a coil spring. They aren’t the same as Huret “Ratchet” shifters at all. They do not even merit searching for a patent as the design is wholly derivative, uninteresting and the actual shifter itself is poor, however they did come in a downtube braze-on mount. Their only saving grace is that even if they are some of the worst ratcheting shifters, they are still ratcheting shifters instead of the plentiful plain shifters that existed at the time.

1983 Huret catalog


Seems to have gone for sale in 1985 or so, but there are some earlier versions floating around that resemble modified Super Record levers rumored to be prototypes. There is a version with a large diameter barrel, making it useful for compatibility with modern derailers and wider cassettes which require more cable pull. It works like a typical one way bearing except instead of the wedges creating a radial force, it creates a force parallel to the direction of the axis of rotation. There is another patent for a different style of a very ugly and inelegant one way clutch (US4878395A). The patent was especially hard to track down because it was not assigned to Campagnolo but instead the bank. People tend to think these are not rebuildable, but with the right technique are easier to disassemble than some others.

Priority: 1984-02-08
Publication: 1985-09-11
Earliest Known Production: 1985(1984 prototype?)

Patent drawing
Are these Campagnolo' Retrofriction/Doppler shifters? - Bike Forums


Another spring clutch design like the Shimano Unishift and Simplex Retrofrictions. Some small parts more closely resemble Campagnolo’s Doppler however, and the tail of the spring is tidily hidden away, contrary to the rough finish.


Many self-proclaimed experts say these were made by Simplex, but Gipiemme looked to be sourcing derailers from Camapgnolo at the time. I highly suspect the “1982” catalog is misdated and is actually 1989+, otherwise GPM would have had a slant parallelogram Syncro 7-speed system years before Campagnolo. Simplex did make Retrofriction shifters for Gipiemme when they sourced rebadged Simplex derailers from them, but the shifters from those years have the same shape as Simplex’s own. There does not appear to be a slot for the spring end and a number of small parts on this spoon shaped version look very different, an odd choice if these are supposed to be made by Simplex just with a different lever shape.

“1982” (1989+) Gipiemme catalog


Dia-Compe now makes a few versions, “Silver” which are copies of Suntour Sprints, one with an extra large barrel for 11 speeds, one styled like a NR/SR lever and one based off of Suntour Command in various mounting options. These are slightly different from the older style Suntour Power shifters which used a stamped steetmetal combination spring and pawl. Like Later Suntour ratcheting shifters, they have an actual pawl and coil spring.


Not necessarily the first, but just to show the spring clutch control lever for a bowden cable goes back further. This patent from 1905 for a lever system not specific to bicycles shows a two-way clutch system like Huret’s, rather than a one-way clutch system like Unishift/Retroshift. While bicycle controls are listed alongside automobile controls as a possible use, as far as I know these were never produced for cycling applications.

Keep in mind, many index shifters have the some of the same advantages as one-way clutch shifters because they work on ratchet and escapement mechanisms. They are irreversible in one direction because of the ratchet, downshifting is mostly friction free because there is no need for friction to resist the spring, and upshifting requires minimal effort, just a tap of the escapement lever.