Carbon Frame & Seatpost Clamp Condundrum

[Andy JB]

So my new MTB carbon frame (Scott Scale) also has a carbon seat post, however, I'm unable to confirm which way round the seat clamp should fit without undue pressure on the carbon, which has no insert.

The cut is at the front of the seat tube (facing the bars), so should the clamp fit backwards ie release bolt over the cut (which is back to front) or reversed to spread the load by fitting normally with clamp towards the rear? There is no consensus online where two carbon products meet each other for clamping force.

The part that does concern me is that my other carbon road frames all have an alloy support to reinforce this vulnerable area - these are not shims, but the Scott just has carbon tube in which the post fits. Perhaps it doesn't matter but I'm not keen on wrecking the frame!!!!!

[arcticnick]

I'd have the bolt-side of the clamp on the same side as the cut-out, ie forwards, as this is where the greatest clamping force will be circumferentially.

Most importantly, make sure that you have carbon friction paste all over the contact points to reduce the force required. I assume you have a torque wrench?

[Benmac]

Dunno if this is quite your frame but it's a carbon Scale. The seat post clamp bolt on this looks to be at the front.

https://www.scott-sports.com/global/en/products/24...

[HardtopManual]

Seatpost clamp bolt on same side of seat tube as the cut-out, plenty of fibre grip between the seatpost and seat tube making sure to cover the entire post/tube contact area, then torque to spec, which may or may not be written on the frame. If you can't find the spec, go for 5Nm.

[Andy JB]

Great to see a consensus - so front fitting to align the cutout with the clamp.

It's a Hope clamp which has the self-adjust lever so adjusting the torque isn't possible but I have a feel for the required pressure as I do use a torque wrench and carbon paste anyway on my other bikes. Its surprising they don't touch on these things as its so easy to go wrong and ruin a frame.

Just got to figure out if tubeless system is worth the effort over a light tube. I've seated the UST tyre & compatible DT Swiss rims without a tube complete with OKO milk sealant but they won't hold the pressure. I suspect new valves are leaking, but I'm not convinced yet.