Has anyone else’s brake bolts been breaking?
For the second time in less than a year I’ve gone to my bike to find that one of the two M5 bar clamp bolts on my tech 3 levers has failed, shearing at the shoulder between head and threads.
It’s happened all on its own, whilst the bike is stored. I torque the bolts to 4nm. The replacement bolt I used this time was an A2 stainless jobbie form Accuscrew. Brakes are bolted onto one up carbon bars, if that’s relevant.
I can’t see any burrs or damage.
Any ideas? Don’t want it to happen when riding!
You got one end of the clamp tight up then squeezing the clamp tight on one bolt?
No issues at all with my 2x (so 4 brakes) sets of tech 3 v4's. My oldest set is 3 years old too.
As above same gap top and bottom to give same strain through bolts.
Same gap not only gives same/similar strain, also eliminates the bending load through the shaft.
Yep same gap. I’m fairly meticulous with such things.
I’ve not crashed it either.
Will take a pic tomorrow, I think the fracture surface is quite interesting too.
Maybe a dodgy batch of bolts? It's probably one of the few parts not made by Hope themselves.
Are the original Hope bolts stainless?
Are the original Hope bolts stainless?
Nope, alloy. M516AL part number.
I'm sure Hope have done their calculations, but an aluminium bolt seems ill-suited to this application. I wouldn't use a stainless bolt either. A normal steel cap screw would probably be twice as strong and barely heavier.
Also, A2 doesnt tell you how strong the bolt is, you need to check the 'Property class' of the screw now fitted. It may well be weedier than the original one.
Thought the MC clamp bolts were steel as normal with Ti being an option.
FWIW I have run std and Ti with no issues.
I had this yesterday! failed with a "ping" as I was attaching the dropper remote to the integrated mount- didint even touch the bolt.
Went to grab a spare off the other bike. and damaged that (fractured the head) too.
The first one on a bike that has barely been ridden all summer. The second, in fairness I did crash on Friday.
both bikes live in a steel asguard shed.
I've ordered some stainless bolts, but I'm now worried about bi-metallic corrosion. the levers are aluminium right?
Yep had this happen a few times with the alloy bolts they provide, each with the same "ping". Replaced with stainless steel and fine ever since.
Always happened randomly when no one was near the bike too
. I wouldn’t use a stainless bolt either. A normal steel cap screw would probably be twice as strong and barely heavier.
An M5 bolt in stainless weighs so little really, An m5x16mm must weigh about 2.5, maybe 3 grams.
Plain steel, and this is something thats likely not going to be touched in a long time, you have the worry of rust. Stainless will not rust. Difference between the two is likely 0.2 gram. In other words so little its not worth bothering about , unless you are some crazed weight weenie.
I broke one recently but was as a result of a big crash so I was glad that was all that broke rather than the lever or bars!
Not just me then! I’ll check the material for the bolt that has broken, and if it is the aluminium original I’ll replace with stainless which I have a big bag of.
And change the rest.
And importantly, the ones on my other half’s bike!
Just checked, it was the aluminium bolt.
Will be changed for something more robust! I get the argument that it’s a decent fuse in a crash, but I’d rather not have the crash because the bolt failed in the first place.
How tight are you doing them up? I never do them up tighter than just enough to not move when in use but so the lever can spin round te bar in a crash, never broken a bolt in over a two decades of using Hope brakes.
Im with reluctant jumper. My bet is over tightening.
I always assumed they used the aluminium bolts there deliberately so that they would break in a crash rather than snapping the expensive levers / bars.
I’ve mooshed / broke one over the years; I find it best to just nip them up rather than torque them to the suggested rate. This may be caused by my cheap torque wrench…
I know the spec for them is 4Nm but in the 8 tech 3 levers in this house, I've never gone past 3Nm and most are closer to 2.75Nm.
I also use feeler gauges to balance the gaps top and bottom. I've not had one snap yet.