Saddle clamp clamp woes!!

arlowood

Just want to check if my problems are unique.

Just finished building up a 2002 era Trek 5200 frame and I'm having real problems with the seatpost clamp. The post came bundled with the frame and is a Bontrager XXX carbon seatpost. You can see it here in the frame at an earlier stage of the build.



It has the single bolt construction which is supposed to allow for infinite adjustment of the saddle angle. Up to now however I've found it virtually impossible to get the saddle clamped level and keep it there. Thought I'd cracked it earlier this week but after only about a mile of riding the saddle had tipped forward with an angle of about 30deg. This despite me tightening the bolt as hard as I dare.

I've seen these on sale at over £100 but also sen them on Ebay for about £35. Just wondering if the lower priced ones are possibly copies and I've got one of those with an inferior clamping set up.

I've seen other seatposts that employ this single bolt design. Have any others out there experienced the same problems

jordan_217

Apparently there's a torque setting of 16 Nm on this post and it's meant to be done to that, otherwise risk creaking and slipping. There's also a rider weight limit of 80Kg. Must be very light for them to put a low rider weight on it?

Just had a quick google around.

HTH

EDIT: That's 16Nm on the rail/saddle clamp

JayKosta

Make sure the contact surfaces are free of grease - clean them soap, or de-greaser.
Also inspect the surfaces to determine if they originally had some sort of texture, or roughness.
If the surface are metal (aluminum?) then perhaps you can add texture by lightly stratching the surfaces with a center punch, awl, drill bit, etc. Maybe something such as 'carbon paste' would help.

Jay Kosta
Endwell NY USA

arlowood

JayKosta wrote:

Make sure the contact surfaces are free of grease - clean them soap, or de-greaser.
Also inspect the surfaces to determine if they originally had some sort of texture, or roughness.
If the surface are metal (aluminum?) then perhaps you can add texture by lightly stratching the surfaces with a center punch, awl, drill bit, etc. Maybe something such as 'carbon paste' would help.

Jay Kosta
Endwell NY USA

Hi Jay

Tks for the suggestion. Have got some carbon paste so will give that a try.

Main problem seems to be the fine adjustment of the seat angle - finding it v. diff. to stop the saddle moving from the horizontal when tightening up the clamp.

Coach H

arlowood wrote:

Have got some carbon paste so will give that a try.

Main problem seems to be the fine adjustment of the seat angle - finding it v. diff. to stop the saddle moving from the horizontal when tightening up the clamp.

I have a Spesh post with the same type of clamp on one bike. With that each time you change saddle you have to free the inner cups (they get semi-fixed in position), clean, grease and then make sure when you have set the saddle angle the inner clamp sections have actually moved and the saddle rails are sitting square in the saddle clamp. If you dont get the inner clamp pieces moving freely and square when you tighten up the rails and outer clamp sections move to match the angle of the inner clamp.