Bicycle Mechanics - Clamp to hard?

Hi, is it bad for the the seatpost to where it is being clamped really tight? Is there a limit that I should know about?

theres not limit except if its carbon fibre

Cool

Find manufacturer torque spec. for seatpost binder bolt. Theres nothing like stripping out that bolt and having it fail on a ride.

Over-tightening the binder bolt can also cause the paint to crack and peel off of the binder and the top of the seat tube.

Find manufacturer torque spec. for seatpost binder bolt. Theres nothing like stripping out that bolt and having it fail on a ride.


These bolts don't just strip, they tend to break in half if over-torqued. Either way, you're off the bike for however long it takes to get a new one.

Bob

theres not limit except if its carbon fibre

Wrong. Of course there are limits to tightening any bolt on a bike, regardless of material.
A too tight bolt could snap or strip under riding conditions.
Refer to the manufacturers specs or general guidlines in bike maintainance books.

I make sure the bolt has good clean threads, lube the seatpost and bolt with grease, then tighten until I can just barely twist the seat post.

you should tighten it until the seatpost cant move anymore

I hate when it does manage to move during riding.

For carbon seat posts do not use grease of any kind. Wipe the inside of the seat tube with a dry rag. If you are careful you can use Acetone which doesn't leave a residue or film. Find the proper location for your seat, but do not over tighten the seat bolt. When you are happy mark the seat post with tape. Spray the seatpost lightly with hairspray (lightly means lightly) insert the post, straighten the seat to the top bar, then apply the proper amount of torque. I use the lower end of the torque range recommended for metal seat posts. Give it some time to dry and your seat post will not move under normal riding conditions. You will still be able to remove the seatpost from the frame with a little coaxing without damaging the part. Another trick if you have a seat tube clamp with the slot in the rear of the ST then reverse the clamp so the clamping ends are not on the same place as the ST slot. It will even the compression on the carbon post.

Not an expert on this, but from the Park Tools book:

"Generally, only tighten the binder until the saddle will not rotate when pressed with one hand. If it will not rotate with one hand, it will not slip down."