Re: Torque wrenches

"Qui si parla Campagnolo " <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

peter-<< They're not essential at all. I can't think of a really
torque-sensitive
fitting on a bike. >><BR><BR>

think, 'crank bolts'....

Crank bolts was indeed the application I had in mind. Certainly crank bolts
can be under-tightened, but can they be over-tightened? The nominal torque
usually given for the typical 8 mm bolt is around 30 ft-lb (pretty much max
torque) where yield might be 40 ft-lb, so tighten too much & the head snaps
off. Lubricating threads, heads, washers, etc. can make a 25% torque
variation, as, in this case, can lubing the tapers. The idea is to get the
right clamp force, torque is an approximation of that. I interpret the crank
bolt spec as "tight as you can w/o popping the head". I've never popped a head
or had a crank loosen, so my impression is that there's a fair amount of
leeway in even that "torque-sensitive" application.

peter-<< Certainly crank bolts
can be under-tightened, but can they be over-tightened? >><BR><BR>

Sure, I have seen many fall off(under tightened) or those having the small ring
resting against the right chainstay(overtightened) and a few with sheared off
crank bolts or split crank arms.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"