Carbon fiber torque spec?

[Rick Onanian]

I'd like to change the stem on my 2001 Giant TCR2. The steer tube (or is that called the riser?) is
carbon fiber, and I'm concerned about tightening the stem to the proper torque, such that it will be
both secure and non- damaging. I've heard of numerous cases of over-tightening things like stems
that clamp onto CF things and crushing the CF.

Of course, OTOH, I wouldn't want to leave it so loose that the handlebar comes off in my hand at
35mph going downhill in automotive traffic...

Thank you,
Rick

 

[Phil Holman]

"Rick Onanian" <[email protected]> wrote in message news[email protected]...
> I'd like to change the stem on my 2001 Giant TCR2. The steer tube (or
is
> that called the riser?) is carbon fiber, and I'm concerned about
tightening
> the stem to the proper torque, such that it will be both secure and
non-
> damaging. I've heard of numerous cases of over-tightening things like
stems
> that clamp onto CF things and crushing the CF.
>
> Of course, OTOH, I wouldn't want to leave it so loose that the
handlebar
> comes off in my hand at 35mph going downhill in automotive traffic...

Carbon fiber seat posts work most of the time in their application and a stem is much less loaded
and should therefore present no problems for a lesser amount of torque. If I consider how the stem
and steerer works and consider the type of loading that would tend to work the stem/steering tube
joint (steering loads, road vibration and to a minor extent, reefing on the handlebars) this gives
me some insight into why it should never be overtightened. Like you say, most problems occur due to
overtightening which IMO is unnecessary.

Phil Holman

 

[Jimp]

Most stem manufacturer web sites list torque settings for the handlebar and steering tube bolts
(sometimes different). I would check there for your particular stem.

"Rick Onanian" <[email protected]> wrote in message news[email protected]...
> I'd like to change the stem on my 2001 Giant TCR2. The steer tube (or is that called the riser?)
> is carbon fiber, and I'm concerned about
tightening
> the stem to the proper torque, such that it will be both secure and non- damaging. I've heard of
> numerous cases of over-tightening things like
stems
> that clamp onto CF things and crushing the CF.
>
> Of course, OTOH, I wouldn't want to leave it so loose that the handlebar comes off in my hand at
> 35mph going downhill in automotive traffic...
>
> Thank you,
> Rick