Integrated shifters (sometimes genericized trademark STI which stands for Shimano Integrated Shifting) are sometimes known by the much maligned, loathed and universally despised term “brifters,” a portmanteau of brake and shifter. They are now standard on current production road bicycles. Some might recognize the major brands and Shimano as the originator of the “brifter” and others who fancy themselves bicycle connoisseurs, experts and gurus might know of some more obscure claims like Joel Evett‘s. Anyone but the staunchest retrogrouch clinging onto the idea “nothing is new” can see that the designs for brifters (minus Retroshift) have come a long way technically and ergonomically.
Electric shifting is not included here because electric shifting brifters are mostly just a game of patent dodging by placing buttons in different locations. Pictures may not be accurate to the original year of introduction but are representative to the style of brifter. Admittedly some of the dates are rather arbitrary and inconsistent, some being based on patent priority dates, some being based on product announcements and some based on model year. Others will turn up I’m sure, there’s at least one more I remember but can’t seem to find.
Here’s an incomplete list from newest to oldest:
A relatively new player in drivetrains from China. It resembles Campagnolo Powershift in shape, but the thumb lever placement is more akin to old Shimano Sora. Easy enough to use from the hoods, but a considerable reach from the drops. Aimed mostly at the Chinese domestic market, you can still buy them from abroad. Price is comparable to Sensah, the backstory may be too. The website looks suspiciously like the SRAM one.
Another relatively new player in drivetrains from China. From what I’ve read it’s a company that consists of former SRAM employees that were abandoned when SRAM moved their factory, which explains the heavy SRAM influence. The brifters operate using SRAM’s doubletap principle but with Shimano’s floppy lever and hood shape. Confusingly some use SRAM pull ratio and others use Shimano. An economy brand, but slightly notable for making a mechanical 2×12 mini-group for only a couple hundred dollars. I’m not exactly sure when these came out, but the company was founded in 2014 but I think these hit the Chinese domestic market a couple years later.
ROTOЯ, manufacturer of cranks and oval chainrings decided it was time to make their own groupset because they were being squeezed out of sponsorship deals. FSA, another crank and chainring manufacturer also developed an electric groupset around this time. Shifting is like SRAM’s DoubleTap, but patent dodging is achieved by using hydraulics instead of cables, making it non-standard and requiring cable stops to be drilled out to allow for full length hose runs. While other brifters have hydraulics for brakes, ROTOЯ is unique among current production for having hydraulics for shifting as well.
NEW MICROSHIFT (2014?)
Microshift showed off a new 11-speed group copying SRAM’s hood shape and Campagnolo’s Ultrashift at trade shows, but the parts only seemed hit the shelves long after Shimano had released 105 5800, making it unappealing and not particularly economical. It’s notable for trying to combine both of Campagnolo’s EPS and traditional thumb tab shapes, something Campagnolo may have taken note of with the new Ekar Ergopowers. Multiple shifts in both directions with Shimano compatibility and without the Ultrashift prices.
A rather simple assembly of a downtube/barend shifter attached to a brake lever (and proud of it). The inventor was shocked that apparently no one had ever invented it before. Purported to have many of the advantages of a downtube/barend shifter, I have never tried them because I never particularly found myself in need of the advantages of a downtube/barend shifter. Not really practical to operate from the drops. They are an ergonomic mystery to me, but their modular design makes them especially useful for niche compatibility issues. If you need brifters for V-brakes and a MTB derailer you can make these work. If you are suspicious of the devilry hidden within other brifters, these will allay your fears.
CAMPAGNOLO POWERSHIFT (2011)
Campagnolo long had a product differentiation problem, and low end groups were cannibalizing the sales of high end groups since they provided very similar performance with a fraction of the markup. This is especially true because Campagnolo did small incremental updates across the board instead of staggered generational trickle down like Shimano. Many small parts and subassemblies were shared between groups, sometimes just finished and marked slightly differently with slightly different hardware, a long standing Campagnolo tradition. Just blazoning groupsets with tier names was not enough, so for 2011, Campagnolo converted their lower end Ergopowers to an escapement mechanism that did not allow for multiple upshifts in a single stroke. This restored prestige to Chorus on up, but devastated Campagnolo users on a budget as they would no longer be able to act snobby about their entry level groupset’s ability to shift multiple gears in both directions. In 2015 the thumb button was changed to mimic the EPS shape, making it easier to reach from the drops and not stick out as much. A fair trade, as one can quickly tap the thumb tab a few times as fast as the bike can shift. If you didn’t tell me that Ultrashift was more expensive and prestigious than Powershift, I would probably take Ultrashift over the older Powershift, but new EPS-style Powershift over Ultrashift.
NEW SHIMANO (2008)
With SRAM DoubleTap on the market, Shimano felt like the odd man out with the flying shift cables and decided to reroute them under the tape with Dura-Ace 7900. The same control scheme as before, but shifter internals moved inside the hoods instead of being on the lever. Controls from the levers were routed with a somewhat convoluted mechanism. The new cable routing meant friction was signifigantly increased, and it was especially noticeable due to Shimano’s high 1.7 actuation ratio at the time, completely changing the feel of Shimano’s previously very light action. This was later mostly fixed with Dura Ace 9000 and Tiagra 4700 which changed the actuation ratio to 1.4.
Evett’s story of inventing brifters gets retold because in 2007 he showed off a new design of his at NAHBS. The thumbwheel is geared and drives a dual cable barrel. Not the first to use a wheel with planetary gears to drive a shift barrel, but the first to be put inside a brake lever body.
OLD MICROSHIFT (2006)
Like Shimano’s old design it has flying shift cables and a shifter attached to the brake levers. Unlike Shimano, it has no floppy brake lever and was reasonably light. Instead it has levers like a MTB thumb shifter, but much smaller, with the long lever behind the brake lever allowing for multiple downshifts, and the short lever for an escapement that allows for single upshifts. It was once frequently rebranded under house brands and considered the affordable alternative to the big three. Now this design seems to have been copied by a company called “MicroNEW.”
SRAM had purchased Sachs in 1997 which in turn purchased Huret in 1980, but SRAM itself had really only been producing MTB components with the Grip Shift (which was not the first handlebar twist grip shifter) as their mainstay, unless you count the early barend Grip Shifters for drop bars. In order to navigate patents, SRAM developed the simple and light DoubleTap system. It has only one shift lever, pushing it in one click activates an escapement causing one upshift, pushing it further deactivates the escapement and makes the shift barrel ratchet for one or more downshifts. Much appreciated people that hate Shimano’s floppy brake lever and have trouble reaching Campagnolo’s thumb tab from the drops. While shifts are snappy, I find I can never seem to shift as fast on SRAM due to the heavy action. Each upshift is deliberate, and each downshift requires going past upshift lever throw. Particularly annoying is when you try to downshift when already in the lowest gear where you must accept an upshift when you don’t want it, or apply an unpleasantly large force to the lever until it gives to cancel the shift with a disconcerting clunk. SRAM is notable for producing some of the lightest components, including brifters. Their lowest tier mechanical/rim Apex brifters weigh less than Dura-Ace and their third tier Rival brifters weigh less than Super Record.
FSA SRL, the company that sells FSA parts made by Tien Hsin, thought about trying to expand into drivetrain components with this design, but apparently did not follow through. The trigger shaped shift lever behind the brake lever is pulled back or pushed inwards to shift, and works on two axes like Shimano’s brake lever. From what I can tell, the trigger motion winds the barrel for downshifts, and the lateral motion is for the escapement causing upshifts.
Mavic had previously made the first electronic groupset, Zap, and some earlier road components, but looked to consider re entering the market with a mechanical brifter. It appears to be another dual axis trigger type where pulling the trigger and pushing it inwards shift gears. It seems a bit unusual for both companies to come up with similar solutions over a decade after Shimano released STI. From what I can tell, the trigger motion winds the barrel for downshifts, and the lateral motion is for the escapement causing upshifts. From what I can tell the controls are opposite of the FSA design, the trigger motion is for the escapement causing upshifts, and the lateral motion winds the barrel for downshifts.
Another Mavic design. The shift mechanism is actually in a separate control box even though the shift levers are integrated into the brake levers. It operates much the same as SRAM eTap, with one side to shift in one direction, and the other to shift in the other direction. It uses grooved cams to manage the shift pattern.
SHIMANO SORA/TOURNEY (2002)
During the long Shimano 9-speed era, Shimano introduced 9-speed Tiagra when Dura-Ace was still 9 speeds. My recollection is this generation Tiagra may have be a touch less smooth and precise, with a slightly heavier and snappier action due to stronger springs, but functionally, worked very well. Having four product lines that do the same thing, just different levels of materials and finish was a bit of a problem for product differentiation. Thus the Sora level was born, replacing the shift lever nested behind the brake lever that must move with the brake lever when downshifting, with a simpler and less conveniently located thumb tab. It let Shimano have an entry level brifter that lacked full functionality. 10 years later, Sora was finanlly upgraded to STI proper, the unbranded 8-speed tier became Claris with STI proper, and this design was moved down to Tourney. I have my suspicions that this design may have been chosen not just for economy, but as a shot at Campagnolo, implying that thumb levers were low-end, and placing it in an even more difficult place to reach from the drops than Campagnolo, subtly implying to the consumer than thumb tabs and by extension Campagnolo were inferior and difficult to use.
MODOLO MORPHOS (1998)
Brake company Modolo saw that it could be pushed out of the market as brifters caught on. Modolo has been attributed by others as having introduced the aero brake lever (before Shimano popularized it) and the delta-style brake (before Shimano then Campagnolo produced their own designs) with their innovative Kronos. They also made some very light weight carbon fiber downtube shifters. The Modolo Morphos seems like the natural result of a third party company that made innovative brakes and shifters but not derailers. Modolo’s brifters have the unique ability to be set for various cable pulls, allowing for compatibility with Shimano and Campagnolo derailers and cassettes in various numbers of speeds. It has two thumb levers, one for upshifting and one for downshifting in a somewhat obtrusive setup, but because all the shift levers are inboard of the brake body, it could almost pass for a vintage brake lever from the side in the silver version.
A previous design attempt by Modolo, but not quite the way it was actually implemented, also with thumb controls but a bit different.
CAMPAGNOLO STRATOS/AVANTI (1994)
A downrange simplification of ergopower. The thumb lever does not operate independently of the other shift lever, but instead they are actually combined. It puts the thumb lever in a less convenient location, and means the shift lever swings out when upshifting.
Someone at Sachs thought they should try to design their own brifter. They took SRAM’s Grip Shift and wrapped it around the brake body instead of a hood. It seems like a recipe for accidental shifting when dancing on the pedals and general safety hazard. It’s little wonder they sold rebranded/modified Ergopowers, or maybe this is why they decided to sell Ergopowers.
The brifter that never was. SIS forced Suntour into bankruptcy, but there was an attempt to revive it as SR Suntour. The Suntour Command shifter was rushed to market, however they had lost so much market share they shut down in 1995. Some Suntour engineers apparently had hopes and dreams that they could revitalize the marque, but it never happened and the name got sold off to a maker of suspension forks. It appears to have worked similar to the Avanti system and even has a little thumb wing like it.
CAMPAGNOLO ERGOPOWER (1992)
With the release of SIS then STI, Campagnolo was forced to follow suit and copy Shimano. Campagnolo gave up on alternative derailer designs completely and made nicely polished Shimano copies with slant parallelograms and dual sprung pivots. While these were things Shimano themselves copied from others, STI was their own invention, so Campagnolo was forced to innovate to make a functional brifter. Some have insisted Sachs must have engineered it because it was too complicated for Italians to engineer and it must have been the result of superior German engineering (Sachs had their New Success group made in collaboration with Campagnolo). I don’t see why this would be the case, the patent is Campagnolo’s, and the listed inventor is listed as inventing many other Campagnolo designs. Sachs patented their own design after. The mechanism is relatively simple, the levers allow the rider to rotate a shift barrel similar to Campagnolo’s downtube Syncro shifters down to the G-springs (the detent mechanism would later be changed and the name changed to Ultrashift). Unlike other brifters, Campagnolo’s have QRs instead of the calipers as part of their ongoing campaign to cause agonizing compatibility issues and preserve the sanctity of the “gruppo.” It also doesn’t use an escapement and ratchet system which gave it the unique (until Microshift copied them) ability to shift multiple gears in both directions, just like a downtube shifter. The incorporation of it into the brake body makes for a tidy and unobtrusive design with no bulbous malignant growth on the brake lever. It also requires the shift cable to be run under the bar tape, restoring the clean look people had come to expect in the age of aero brake levers. Shift cables are more sensitive to friction than brakes, so the hood shape had to be altered to provide a smoother transition to the handlebars than Shimano. This led to the flat and level perch which has become standard in hood design and ergonomics and eventually led to the compact bar. Even Shimano copied this part of the hood shape before they put the cables under the bar tape. Because the lever actions must act in opposite directions (like moving a downtube shifter in opposite directions) Campagnolo levers have a rather unusual inboard thumb tab. This feature(bug?) is touted by many Campagnolo users and Campagnolo itself as each action has a unique motion and separate unshared control lever. Braking requires pulling on the brake lever as is expected. Upshifting is done by pushing on the thumb tab. Downshifting is done by pushing the shift lever. One of those instances where patents forced a competitor to innovate.
I will have to take a closer look at this patent, but it appears to be a twist grip type design like the Sachs unit. It seems bad for the same reasons.
Desperate to come up with a solution to chase STI, Campagnolo came up with this twist grip knob mounted on the hoods prior to Ergopowers. I think all Campagnolo aficionados are grateful that they didn’t rush it and end up with this.
SHIMANO TOTAL INTEGRATION (1990)
After gaining market dominance with SIS index shifting, Shimano felt it was time for another innovation to seize even more market share. Not content to just sit on SIS, Shimano created the first modern brifter by adapting their rapidfire MTB shifters to road. It had working index shifting, return-to-neutral gear levers, and all controls (braking, upshifting and downshifting) were accessible from both the hoods and the drops without awkwardly having to change hand position. Some may choose to deride it as undeserving of being known as the first brifter, but it was a landmark achievement nonetheless which has had a permanent impact on the industry. While mounting the shifting mechanism to the brake lever makes implementation simpler, it requires a flying shift cable. That gently curved flying cable inline with the shift barrel makes for a very smooth and light action, something sorely missed when Shimano went to under the tape cable routing. Going the Microshift route may have been simpler, but it seems Shimano felt having all controls readily at your fingertips in both the hoods and the drops was important, much to the chagrin of clumsy full-finger gloved cyclists lacking fine motor control. Shimano instead decided to make the brake lever move on gimbals in two axes, something not copied until Sensah. It was touted as letting you shift under pedal load (true), shift while cornering (also true), shift easily while climbing, even standing, (true again) and shift without letting go of the bars in poor conditions (truer still). These are things I would hesitate to say were true of other prior designs, especially if considering usability from both the hoods and the drops. Shimano understood how brifters would change road cycling if only they were widely adopted, and now they are. Having a manufacturing and engineering titan like Shimano behind this idea was a gamechanger. The result is very usable and has many grand tour wins (less so now with Di2 which is closer to the Microshift setup). The brake lever is pulled back for braking, pushed inwards for one or more downshifts, and the shift lever triggers an escapement which upshifts one gear at a time. Some people hate the floppy brake lever, but it’s never given me a problem.
SUNTOUR COMMAND (1990)
Not really a brifter but it gets an honorary mention. It’s a bar mount shifter that gets mounted near the brakes with two wings so you can push with your thumb in both directions from the hoods. Simple and effective (from the hoods). Some say it made it to market before STI, but mounting gear levers near brakes is not particularly novel. It’s been done on drop bar IGH (indexed too) bikes, probably since before full wrap bar tape and grippable hoods were a thing, just moving the flat bar configuration to early drop bars. Dia-Compe makes a shiny silver modern production friction version under their ENE brand for retrogrouches with an identity crisis.
The Betätigungsvorrichtung. Although technically the Shimano patent priority date came first in ’88, it shows an interesting attempt with indexing and aero cable routing. It seems usable, although pales compared to the ergonomics of modern brifters.
An even more integrated solution much like Smolik’s but with aero cabling. The internals have been redesigned and the trigger is nested behind the brake lever, but it still works on the principle of pushing or pulling a small lever behind the brake lever.
The priority date for STI proper was also in ’88, but this apparently shows an alternative design Shimano was working on at the same time or prior. Perhaps Shimano assigned the conservative road and radical MTB engineers to design one each. It’s similar to Smolik’s with a return-to-neutral trigger with the barrel hidden inside the brake lever body. The drawings seem reasonably detailed rather than just conceptual drawings and show internals similar to Shimano’s index downtube shifter mechanisms and their road brake levers. The design that could have been if Shimano hadn’t been so bold. To what degree would retrogrouches even exist if Shimano released such an inoffensive and incremental design? No flying shift cable, aesthetics near identical to their prior offerings, no bulbous growths, no floppy brake lever and a simple and easy to understand design. I think I rather prefer STI as actually implemented though.
Shift by twisting the grips along the z-axis. No thank you.
Yet an older index design (pre-SIS), the schrittschalteinrichtung, with a shift lever behind the brake lever, and a similar mechanism to Campagnolo but along another axis and with only one lever, like Avanti. Made by Smolik, an extreme weight weenie of some reknown. It seems to be one of the earliest designs with return-to-neutral so the lever is always within reach, but it does seem a bit awkward to use.
It’s a bit difficult to understand what’s going on in this patent. The strange bullhorn to drop bar brakes are found in other patents, so this possibly relates to gear shifters in the hoods. However the illustrations don’t show brake levers. Unfortunately what translation is available is poor and I don’t feel like attempting a translation, but the drawings are shown here. It seems like a small jump from these gear shift designs to one that also adds a brake lever, but I did not find a patent with such a drawing.
Technically not a brifter, it’s just mounts near the brakes like a Suntour Command. On second thought perhaps it’s actually a brake lever design to improve braking from the hoods. I will have to go back and review the patent in poorly scanned Japanese to check. Apparently the top and bottom halves can move independently, the top half acting like an interrupter brake moving the housing. A strange solution.
Shimano was thinking about actual brifters even before SIS, but not in any recognizable way. Bar end shifters on bullhorns with reverse guidonnet levers. This was leading into the age of the funny bike, before aerobars. Perhaps Shimano thought nothing would look too strange on a funny bike. Perhaps Shimano thought bike boomers who only ride on the tops were going to buy new funny bikes instead of drop bar bikes. The idea never took off, and you never see bar end shifters on funny bikes even though they used reversed road brake levers, not bar end brake levers. Another patent has the bend built into the lever bodies, so perhaps shimano wanted some kind of modular bullhorn based system. I have to wonder if someone on the Shimano design team for Metrea had a soft spot for these.
Maybe you’ve heard it before, as Evett likes to tell it, he’s responsible for STI a decade before it happened. Shimano requested a prototype, then sent it back without comment, or so the story goes. Shimano’s first brifter attempt didn’t look much like this. His story has gotten some exposure in the press. If he sent it after 1980, clearly Shimano already had their own ideas. If he sent it before, he may have inspired some Shimano R&D looking into the idea, but the reason they sent it back was because they felt it was unworkable from a practical standpoint even with their own takes on it. Even if he sent one to Shimano, the design is much closer to Campagnolo who supposedly dismissed it as a novelty. The primary difference is the Campagnolo thumb lever has a return-to-neutral mechanism and has an additional gear shift lever behind the brake lever also with a return-to-neutral mechanism to rotate it the other way. To his credit it may be the first one that has a mechanical shifter actually integrated semi-internally to the brake lever body, rather than an external mount attached to the brake lever body. The design seems to be fairly usable but can get in the way of your thumb.
Design by Yoshimi Ryuuichirou, it mounts the shift lever on the brake lever, but I wonder if shifting ever led to accidental braking.
Perhaps better known for the salmon red colored brake pads, (Everett, the industrial supplier of the compound would later go on to found Koolstop) Mathauser also designed things like hydraulic rim brakes, but also an indexed hydraulic brifter. Note the shift lever shape to make it accessible from both the hoods and the drops. The hoses are aero routers, and the high pivot point necessitated by the hydraulics should make for decent braking at the hoods even prior to mechanical aero brakes.
Renowned genius engineer Tetsuo Maeda of Maeda Iron Works is well known for revolutionizing bicycle shifting and leaving a permanent mark on the industry with his breakthrough invention in 1964. The invention of course being the Suntour Gran-Prix, the first slant parallelogram derailer. 3 years later he came up with this remarkably simple design to adapt an off the shelf Dia-Compe-style brake lever by replacing the bar clamp stud with one with a shifter boss on the other side. While the detail shows a flat bar lever, another illustration also shows it mounted on drop bars. Unfortunately in 1966 Yoshigai Kikai Kinzoku KK, better known as Dia-Compe, had filed a patent for “safety” levers which attached to the same point and the bike boom happened. For a riders that only rode on the tops, stem shifters and “safety” levers make more sense. Dia-Compe sold countless “safety” levers and none of these. The design seems fairly usable, but like “safety” levers, they do seem to get in the way of your thumb limiting the usefulness of the hoods from which you were to shift from.
A French design seemingly based off of a LAM brake lever and Simplex shift lever but modified enough that it would be difficult to utilize many of the original parts it was based off of. Naturally, since it predates the Campagnolo Gran Sport, it’s French. Note that the illustration is a right hand lever so if the lever can not be manipulated from the hood, it can more or less be used like a downtube shifter without reaching for the downtube. The cable does seem rather obtrusive though.
MAURY of MAYSOUNABE (1951)
It resembles Retroshift, but the star shaped lever means some part of the shift lever is always in reach. Note that the brake body seems to wrap around the brake lever to create a stationary shifter mount, unlike Retroshift where it is attached directly to the moving brake lever (on aero brakes the part of the lever above the pivot moves forward, which is why Retroshift doesn’t do this). Single cable for Simplex. Clever solution for a lack of return-to-neutral, but it looks a bit like a faucet handle. Not content to merely have shifting at his fingertips, the other brake lever sports a lever for the dynamo and a bell. One has to wonder how comfortable holding onto and trying to brake from the hoods is though.
A Cyclo shift lever mounted forward of the brake lever, but modified with a thumb wing for easy access by both the thumb and the fingers with only pushing. Again, mounted to the body, not the lever itself as the cable stops are part of the body. Mounted to a personal bike of Georges Navet, founder of Specialties T.A., yet never actually put into production as he focused on other products such as cranks. It appears to be a simple yet effective design.
Likely the same, or nearly the same as above, possibly without the additional thumb wing. Note that the brake lever bracket wraps around the front of the lever. There’s not much clearance depending on lever position for braking from the hoods, no matter how ineffective braking from the hoods is for traditional brake levers. Given the shape of the brake lever body, maybe braking from the hoods wasn’t considered at all.
Again by Georges Navet. This configuration would not have been possible with a Cyclo dual cable shifter, which might explain the change. Curiously this one has raised cable stops which are specifically listed as an ergonomic feature whereas the 1947 version does not. Note that this was invented before Specialties T.A. was founded in 1947. The wedge instead of a clamp is a nice touch. Although it shows a dual cable lever it also shows how small it must be, much smaller than the very large Cyclo barrel.
Debatable if this is a brifter. According to the description, it is in fact a gear lever attached to a brake lever clamp. The brake lever is curved like a road brake, but not oriented to the handlebar clamp correctly, and this particular orientation would make grabbing onto the brake lever body difficult. The clamp and lever body itself does not really resemble a road brake lever even for the 30’s.
Even if the idea of a “brifter” stretches back over half a century, there’s some very real differences in terms of usability and ergonomics between those designs and those of today, differences that made old designs a novelty and modern ones standard. Mounting shift levers near brake levers is not a new idea. Handlebar mounted shift levers are over a century old, and early drop bars were conceived as a way to get the grips lower, not so much for multiple hand positions. Naturally flat bar brake and shift levers were moved to be accessible from the drops, but with little consideration to their usability from other hand positions. Contrary to the “it’s been done before” and “nothing new under the sun” retrogrouchy folks there were very real developments in design:
Steering while shifting – A main goal of the first brifters was to put the shift levers on the handlebars to allow for shifting without letting go of the handlebars, putting it near the brakes and the hands. However, this was arguably achieved even before brifters and grippable brake hoods. Early attempts seem to be more of an exercise in not wasting valuable handlebar real estate and getting the shift levers in a place both easily accessible and out of the way such as Navet’s 1946 design and also accomplished by bar end shifters.
Finger flexion controls – Fingers are stronger in flexion (curling the fingers toward the palm) than extension (uncurling the fingers outwards). Requiring finger extension is a flaw of many of these designs. On a traditional downtube lever, there are numerous ways to grip it, but requiring a change in grip on a brifter is a flaw. Navet’s 1949 design makes a concession towards this with the double tipped lever.
Usable from the hoods and the drops – Racers have been grabbing the hoods since at least the 30’s, and been in the drops longer still. The first design that seems to really take both the hoods and drops into consideration is the 1971 Mathauser design. The brake pivot is high and forward because of the hydraulics, so the usability of the brake lever from the hood should also be good. Earlier designs seem to be more about finding a decent mounting point in the vicinity of the hands.
Return-to-neutral levers – Ensures levers are always both accessible and out of the way as applied in Smolik’s 1981 design. Many of the compromises of other designs are due to the shift lever requiring a large range of motion. A lever in a certain position may get in the way limiting design or being obtrusive, or be out of reach from a certain hand position or using certain digits requiring a change in grip or a difficult reach. It is a major step in usability and allowing for better ergonomic placement.
Index shifting – IGHs had index shifting, so did a few derailer designs, but either had few gears or were unreliable until modern developments. I would really attribute this to Shimano SIS and further developments introduced in 1984. Working index shifting is least of all about the shifters. It’s about the derailer, but also about the chain and tooth profiles, something Shimano understood more than the competition. Many of the functional advantages of brifters rely on instant shifting and brifters are part of a system that allows for instant shifting. Indexing and brifters complement each other well. The use cases of wanting to shift while holding the bar to maintain control or shift under load benefit from indexed shifting so you can shift quickly and focus on other things. The ability of indexed drivetrains to shift near instantly is hampered by having to reach for the downtube instead of having shift controls at your fingertips.
All of the above – Arguably done by Shimano STI, which is why they caught on and Shimano is considered the first real brifter that succeeded, and it wasn’t just manufacturing or marketing prowess. Shimano STI introduced brifters to the world as we know them today, both by being the first mass produced ones, but also solving design issues in prior designs and pairing them with indexing. Further developments on the brifter are mostly refinements or patent dodging, with advantages and disadvantages being more subjective in nature.