Originally Posted by
FloridaDave
Hi, all. Just bought a new carbon fiber bike (Giant Fastroad flat bar road bike) and I'm having a problem with a rattle in the saddle. I've narrowed the noise to the saddle by eliminating other possibilities. I can bounce on the saddle or slide myself fore/aft and make the noise. Nothing else does it.
Unfortunately my Giant dealer is an hour away and all I've been able to do so far is discuss the issue with him by phone. He believes that the noise comes from either the seatpost bolt not being tight enough, or the clamp that fits over the seat rails isn't tight enough.
All of that is the backstory for my real question. How real of a threat is over-torquing and damaging a carbon bike?
Giant labels all the the bolt torquing requirements right on the bike, in N-m. I don't currently have a torque wrench to tighten to spec. I can buy one -- they're not horribly expensive. However, my bike dealer is assuring me that I cannot over-torque these bolts and to have at it.
I'm currently using 3" long allen wrenches so it's pretty hard to generate a lot of torque. I fear the nightmare of over-tightening and snapping the CF, if that's even possible. Any thoughts on torquing bolts on a carbon fiber bike, and is a torque wrench necessary for routine, at-home maintenance and adjustments?
Thanks for your thoughts, ideas, and warnings!!
If you haven’t used carbon paste on the post you might start with that. I have the Finish Line brand. A tube is less than 10$. It has the consistency of Vaseline but with some fine grit in it. I’ve heard that the use of this paste goes a long way with carbon frames/seatposts to keep things quiet and prevent over torquing bolts.
As for the torque wrench, I would say go ahead and get one. I wouldn’t recommend the Harbor Freight one since it is crude and you have to convert inch pounds to Newton Meters. One that is bike specific might be more versatile and easier to use. The Park Tools T-shaped ones with preset clicks would probably work for you.
One tip I would share is that “T” shaped wrenches can help with applying even torque that you can feel. It is like you double the force so you’re able to really snug up a fastener much more reliably than with an “L” shaped wrench that can slip off, strip out the bolt head, or fly off at a weird angle and scratch the frame.
Be sure to post an update when you get this issue sorted. Let us know what you learned and if you are able to isolate the exact cause of the noise. I’ve got a vintage titanium bike where my Ritchey carbon fiber fork either creaks or rotates to the side during rides. I think I have the solution but I have not fully implemented it yet (I’m waiting for a slightly different dimension sleeve to arrive from China - 27.2-30.1 vs 27.2-30.0. My frame is normally takes an odd size seatpost 30.0 but is now sleeved to take the more common 27.2 size post).