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Campagnolo Power Torque crank - lose

Posted: Tue Apr 08, 2014 6:57 pm
by Devon
So I had a local mechanic fit my crank to my new frame as he had the required tools. First ride, the crank falls off after 30km.

I give it a good look over and the crank (non-driveside) is freely sliding on and off the splined axle. I distinctly remember this being impossible when I originally fitted the crank to my old bike as it was such a tight fit (and hence the need for a crank puller). This is no longer the case.

He's fitted it back on for me but considering it's only being held on by the securing bolt/screw I can't trust it enough to ride the bike.

Has he broken my crank? What should I do?

Re: Campagnolo Power Torque crank - lose

Posted: Tue Apr 08, 2014 7:15 pm
by bikerjulio
Sounds like your local guy was missing a required tool - a torque wrench, and guessed wrong.

This is nice example as to why you should buy the tools and do it yourself.

So, you gave him a second chance?

I don't think we are able to forecast over the internet if it's going to be OK or not. Either you trust the guy or you don't.

Re: Campagnolo Power Torque crank - lose

Posted: Tue Apr 08, 2014 7:15 pm
by Weenie

Re: Campagnolo Power Torque crank - lose

Posted: Tue Apr 08, 2014 7:24 pm
by Devon
The way I see it it's his responsibility to fix it. The thing I'm concerned about is that a torque wrench shouldn't be required. The non-driveside crank arm should be held in by friction on the tight fit spline and therefore stay in weather you have the securing bolt there or not, but in my case, the securing bolt is the only thing holding the arm on.

I'm taking it to another shop for a second opinion tomorrow but would basically like as much evidence as possible to take this guy down - if it's broken, he owes me a crank.

Re: Campagnolo Power Torque crank - lose

Posted: Tue Apr 08, 2014 8:42 pm
by graeme_f_k
Hi Devon

A torque wrench *is* required - that is why Campagnolo give a torque setting for the axle end bolt.

If the crank is not driven the correct distance up the splines, which are tapered, it can fret and deform and will indeed eventually fall off - it will behave in essence just like an under-tightened square taper crank.

It may be that the splines are also damaged, careful examination required by (we would advise) ourselves if you are in the UK, or someone very familiar with PowerTorque and who has spare units to cross-check against.

You don't say if the crank is alloy or carbon - it may be that the alloy insert, for whatever reason, has failed in the carbon, if it's the carbon crank, so allowing you to push the crank freely up the splines of the BB axle - as I would be surprised if wear caused in a single 30km ride was enough to make this possible, though it does of course depend how far up the splines the crank will push by hand.

This is not a problem that Campagnolo have an case open for at Vicenza as far as I know, so it sounds as if it *may* be a fitting error - but every (potentially) warranty-type case has a first occurrence, so it would be useful for a Service Centre to look at this for you.

HTH
Graeme