Tuning UT cranks - alloy main bolt?

[Bridgeman]

I broke a collar bone as a result of a crankarm failure during sprint intervals. It was an extensive injury. Failure of this bolt could result in a similar injury, or worse.

There is no way I'd replace the stock bolt for an unknown quantity.

[Calnago]

Second that... Why on earth would you want to be messing with such a critical bolt. Just crazy. No idea.

[kgt]

+1

[kman]

So replacing a steel bolt with ti is not a good idea....? Better tell campag to get rid of the SR ti bolts then. Oh, tell the hundreds of ww members who've put ti bolts on their stems as well. Unless you consider handle bars falling off to be acceptable?

This forum is still called weight weenies, right?

[5 8 5]

kman, I think you're missing the point. It's not about using a Ti bolt. It's the bolt you've used. It does look how shall I put it a little flimsy.

I'd very interested to see what the max torque spec of the bolt is as Campag recommend using 42-60Nm.

[spud]

kman, the difference is that the Campy bolt is engineered for the purpose. As we know, the is a huge range of material and fabrication methods/tolerances. It's why we have such technical grading of bolts. I'd be VEERY leery about using "a bolt" in such a critical fastener. As hard a life as stem fastener has, this one is harder, getting a significant bending moment put through it on every cycle.

[Calnago]

And I believe Campy has beefed this particular bolt up even a bit further than what it was recently. I have Super Record. It has a ti bolt. But it is made and engineered for it's purpose. There's no way I'm trusting that bolt to a different one. For what, a few grams?

I've never seen one break in my experience, but there was a poster on this site who actually had one break and posted pics. It wasn't a good ending. It's the only one I've ever heard of breaking, and since then I take extra care when assembling to make sure that the inner face of the crank, the washer on the bolt, and in between the washer and the bolt are completely free of any possible debris (like a grain of sand or something) that could even remotely possibly cause a stress riser on that bolt when torqued down.