I noticed that one of the bolts used to attach the brake to the fork is stripped and found many solutions but wanted to know if continued use will make it worse with and without repairing it. Also what is the cheapest way going about repairing it?
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4What kind of brakes? We need a lot more detail, but brakes are important safety feature, cheapest fix is not the best approach.– mattnzSep 28, 2021 at 2:15
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3And what kind of fork?– CarelSep 28, 2021 at 6:20
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2Is replacing the fork one of the solution you found? because it is the only reliable one.– EarlGreySep 28, 2021 at 7:00
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2One of the nice things about IS disc mounts is that the part with the female threads is replaceable and simple, but IS is uncommon on new bikes. Post- and flat-mount put the threads in the fork. So we really need pictures and/or specs– Chris HSep 29, 2021 at 12:20
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@Chris H I believe flat mount has the threads in the caliper, does it not?– MaplePandaSep 29, 2021 at 15:10
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3 Answers
Regardless of whats wrong - a brake is a critical component of your bike and you should not take risks.
If your brakes are malfunctioning, stop riding the bike until its fixed.
Don't be tempted to take the brake off and ride anyway, that's foolish.
The common fix for a stripped thread is to install a thread insert, often called a "helicoil" But that may not be suitable, it requires drilling out some metal, and then adding a larger thread into the fresh metal.
If you have an IS mount brake caliper then there may not be enough meat to drill, leaving a thin mount and insufficient metal to hold your braking forces.
For most stripped holes, prevention is better than a cure. However you're probably past that point. Threads strip when the bolt
- gets over-torqued (use a torque wrench)
- has motion/slop (do it up tighter, and use threadlocker to minimise vibration)
- bolt was cheap/underspecced and stretched during use/installation
- the hole was into aluminium, which is soft and threads often don't last.
So avoid those where possible.
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3Suspension fork lowers are made of magnesium, which is equally as soft as aluminum and even more susceptible to corrosion. Thought that was a relevant bit of info. Sep 28, 2021 at 6:41
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1@MaplePanda good point, but magnesium fork parts are still pretty rare AFAICT– Chris HSep 29, 2021 at 12:13
I am going to assume you're talking about a stripped post mount.
As others have said, don't ride even a little with only one bolt. That risks overloading the remaining bolt and causing a brake failure and/or additional damage to the parts.
In some instances they can get stripped because someone put in too short of a bolt. If it's only a matter of a relatively small section being stripped but with lots of good thread beneath it, just using an extra long bolt can work, and if that is the situation then that's probably the cheapest. It would still be ideal to chase and clean the threads before doing this. Post mount is M6x1.
I've helicoiled a number of stripped fork post mounts (probably 5 or 6 now). Most or all of those have been basic OEM suspension forks with chunky post mounts where material loss is simply not much of a concern, i.e. you're going to a 7mm hole from 6mm in a post mount where the face is about a 12x12mm square shape. I've seen some hybrid and road forks where it would be a closer call.
Helicoiling is cheap relative to a new fork, and in most situations there is no other option to save a fork with a stripped post mount. Helicoil kits are somewhat expensive, so you'd have a shop do it.
The upshot with helicoil is there's no strength loss at all as long as there's sufficient material left around the hole. It stands alone in that regard.
answered Sep 28, 2021 at 21:20
You do not have two bolts for safety (i.e. if one fails, you have another one).
You have two (or more) bolts because each one is fundamental. When one is gone, the brake will not function properly and soon also the other bolt(s) will strip/break.
Stop riding that fork.
