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One delicate and valuable part on a bike, the rear derailleur, is attached by a sacrificial part. The derailleur hanger is designed to be weak and to bend on impact, sparing the derailleur and the frame.

The brifter appears to be even more delicate. We never see its inside, and Calvin Jones makes it sound like he himself hasn't taken one apart. Perhaps there are no user-replaceable parts inside it to begin with.

Are brifters meant to spin/slide on impact, by the choice of a low attachment-bolt torque? (And how delicate are road bike brifters anyway?)

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    Mainly, there's no need for a sturdier attachment, since the brifter will not tend to slide/twist under normal operating forces. Jul 5 at 2:41
  • @DanielRHicks Should we be facilitating its sliding/twisting, to spare it damage on impact? We would never want the stem bolts to be tightened any less than just right, lest we lose control of steering, or spin the handlebars (and fly over them if we're not clipped in), but if the brifters shifted slightly from an aggressive move, it's not the end of the world, and a milder torque might help save them on impact.
    – Sam
    Jul 5 at 2:43
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    The likelihood of brifter damage in an accident is relatively low. They should be tightened well enough that one is confident they will not slip in use (an action which very well might cause an accident). Jul 5 at 2:53

4 Answers 4

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I am not privy to the design philosophies of SRAM, Shimano or any manufacturer and as such my answer is based solely on my own experience.

I have crashed on bikes with both Shimano Sora and Dura-Ace shifters and found the shifters have rotated on the bars. There was no damage other than scuffing of the hoods and the plastic shifter body. All I had to do was reposition the shifter on the bars. Functionally they were fine. I always tighten the clamp bolts to the correct torque using a torque wrench (important also to avoid damage to the shifter, clamp, and bars, especially in the case of carbon fibre).

Having taken apart an (already broken) Dura-Ace 7900 shifter, I can confirm that the internals appear extremely delicate and fiddly, and certainly not intended for end users to repair. However, I have never had one fail as a result of a crash.

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    Great first answer, welcome to the site!
    – MaplePanda
    Jul 5 at 5:22
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Generally you'll find that if you torque them to spec, yes they can still twist readily in a serious impact. I don't know that there's a lot of other evidence in either direction what the intent is unless an engineer from one of the component group makers wants to chime in with proprietary knowledge. At that point the question becomes whether they could easily make a more slip-resistant interface if they wanted to. I think the answer there is probably, because the band clamps used are slick, and in some cases even polished, stainless. They could easily stamp a texture into it, but they don't.

The further question could be asked whether the texture some carbon bar makers apply in the lever area is trying to prevent it from ever slipping so it doesn't damage the bar, whether it's trying to make it more secure when torqued minimally, or both. I think the answer is basically that it's only there to make it more secure when torqued minimally, and I think that if you do torque it minimally it will generally still be able to move in a crash. I haven't tested that a lot because I don't usually know the torque value used on the levers of a crashed bike I'm examining after the fact, and the torque present at the bolt after they've been twisted isn't necessarily representative anymore.

How delicate brifters are can't be answer categorically, in terms of impact resistance or otherwise. There are too many at this point. It's also a wholly different question from how complex they are. Doubletap and Pre-Escape Ergo are both far simpler than all the but the earliest STI generations, for example. Generally speaking, brifter internals dying from external impact can happen but it's not one of the more common failure types. With STI, a very common one is failure from the internals being over-stressed on the release click when the FD high limit is too far in. Shifting with too much force at the lever in general seems to be a recurring theme as well.

External impact does sometimes cause the body of the lever to get cracked. Anecdotally I would say a lot of the ones I've replaced over the years where that's been the case (which again is a minority) were in accidents too severe for one to necessarily expect something like the band clamp torque allowing slippage or not to be a big factor.

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  • I've had a few impacts on my Sora ones, never up to cracking, but some deep abrasions combined with rotation . One did seem to start a degradation in the shifting that eventually became severe enough for me to replace the brifter. But it also had at least 20000km on it. The failure mode you discuss for STI may have contributed, as I was riding with it wonky for a little while and shifting seemed stiff - but that was during my recovery from the same crash and everything was a bit off.
    – Chris H
    Jul 6 at 15:15
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IDK about road, but MTB controls are intentionally relatively loose for exactly the reason you describe:

"Brake levers and other handlebar controls should not be clamped down too tight, but just enough to remain stable in use while still being able to rotate in a crash. This helps avoid damaging the controls." https://www.vitalmtb.com/features/Vital-MTB-How-To-Cockpit-Set-Up,1490

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My opinion is that you shouldn't under-torque your brake levers, regardless of whether they are cheap brake-only levers or more expensive shifter/brake levers.

I bought an e-road-bike from a shop where the mechanic instructed that the holder for the bike computer should be under-torqued to protect it when crashing. The same holder was the holder of the front light. As a result of that, it was impossible to permanently align the front light for optimal visibility and no blinding oncoming traffic. Every time I touched the computer, I messed up the light adjustment. Then I torqued that bolt to the correct torque, carefully aligning the front light. I have never after that had to re-align the front light.

After they did the first service to the bike, I started riding it again and soon after that found that one of my brake levers was misaligned. I hadn't crashed and I'm sure nothing other than my hands touched the brake lever. At home, I realigned the brake lever, finding it was very easy to turn, so easy you could turn it accidentally just by riding the bike. Then I checked the bolt torques and both levers were under-torqued. I was certain that during the first service, the mechanic thought to "help me" by under-torquing each and every bolt on my bike.

I tightened those bolts to proper torque. I have had never again to re-align the brake lever. It stays in the current position.

The problem with under-torquing is that if you under-torque by little, vibration is going to slowly loosen the bolt. You will have to re-torque the bolts to a too-low torque every 200 km or else the part will be completely loose. On the other hand, if you torque properly, vibration will not loosen it and the part stays attached and in position forever.

I no longer use the services of that particular bike shop. Not only because of the under-torquing problem, but also because the bike shop seems to use Park Tool Allen keys that have a ball-end and a normal end, and the bike mechanic seems to do all the tightening with the easily accessible ball-end using the large handle in the tool, not using the normal end at all for final tightening. I personally think that Park Tool has caused a lot of damage for great many cyclists by making tools that allow easily applying a lot of torque using the ball end. The ball end damages bolt heads in such a manner that they won't anymore take an Allen key that is a tight fit (and the tighter the fit, the better, because tighter fit damages the heads the least).

It's true that combined brake/shifter levers are expensive and fragile. But so is your time. Checking adjustment and re-tightening bolts to a too-low torque every 200 km costs a lot of your time. The solution to brake/shifter levers being expensive and fragile is to use brake-only levers and bar-end shifters. Unfortunately, we can't do that anymore since modern hydraulic levers aren't available without shifting function.

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  • I also feel that way about the way the big 'p' handle wrenches get used, inappropriate torque for the ball end.
    – Swifty
    Jul 5 at 19:29

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