Hey all, I’m trying to understand what’s going on here because this doesn’t make sense.
I bought a brand new Scott Addict 20 (2025) about 15 days ago.
First thing I did was swap the stock seatpost for a lightweight straight carbon post (DEDA). After installing it, the post got crushed/pinched at the clamp area.
I assumed maybe it was the post, so I reinstalled the original Scott seatpost, and the exact same thing happened again — pinched in the same spot.
In both cases:
• I used carbon assembly paste
• I tightened with a torque wrench to max 4 Nm (clamp says max is 5 Nm)
• No overtightening at all
• The damage happens right at the clamp zone
Important detail:
👉 I’ve been aligning the seatpost clamp slit with the frame slit (same direction), thinking that was the correct way.
Now I’m reading that maybe this is wrong and they should be offset… but here’s my concern:
If I rotate the clamp, then the compression would be applied more directly onto the solid carbon side of the frame (not the slit side), and I’m honestly worried about damaging the frame itself instead of the seatpost.
So now I’m stuck:
• Two seatposts damaged
• Correct torque
• Carbon paste used
• No visible burrs or sharp edges inside the seat tube
• Brand new bike
I’ve already contacted the shop I bought it from and told them the seatpost is damaged and asked for a solution.
At this point I feel like something is fundamentally wrong, because crushing two posts under 4 Nm shouldn’t happen.
Any insight from mechanics would be hugely appreciated.
by juudhartbd
22 Comments
Poorly Calibrated torque wrench potentially ?
Did you ever leave the torque wrench wound out before you stored it? Because 4nm shouldn’t crush a seatpost even if you had the slits of the collar and tube aligned.
I’m not a mechanic.
What’s the manufacturer of the seatpost say to torque it to? The seat post clamp and the seatpost have two different torque specs. The seatpost clamp may have a max torque of 5nm but the seatpost might have a max of 3.5nm.
As a start,is 4nm the lowest torque you can do without the post moving?
yes anything lower i could move it
Best guesses:
1. Your torque wrench is off or incorrectly set, you should compare it to a known good wrench (preferably on a different part that won’t crack) and see if they create the same amount of bolt tension
2: Seatpost tube is undersized, still shouldn’t cause a seatpost to break but it may introduce initial tension that will be on top of the tension of the clamp
At 5nm you can’t crash anything.
Is the torque value with a greased bolt or dry bolt?
Big difference between the two.
Make sure the threads, male and female, are clean of grease. Grease will substantially increase the clamping force for any given torque.
Ditch the torque wrench. Make sure there’s no grease on the threads of the bolt or nut. Put previously cracked seat post in seat post hole, and insert it to where cracks aren’t present. Tighten by hand with a regular or T-handle Allen key or a very short ratchet. Go until you think you’ve got it tight enough.
If you don’t crack it, take it apart and do it all over with a new seat post. If you do crack it? Well then keep trying until you get a feel for how much is too much.
should i turn it around the clamp or i risk breaking the actual frame support of the clamp?
At this point the only correct thing to do is to take it to dealer or contact Scott directly, you brought it new and have an issue and see what they say.
Visual pinching is somewhat usual on carbon post as the first thing it does it compress the lacquer, assume the seat post is correct size, normally it’s not structural
I bet this ends up being something weird, I’d start with the easy stuff and check the manual that there’s not a specified way to have the clamp orientated (ie bolt forwards) it looks like the wall thickness isn’t even, so it may be designed for something like that (although that may just be the photo angle)
Then I’d look at the roundness of the clamp and seat tube, clamp, and post inner/outer
Double check the torque wrench, it shouldn’t move a bolt torqued by a known good wrench.
I’d definitely be tempted to try the clamp backwards (if not expressly forbidden), a little grease underneath, it will spread the clamping rather than focusing it.
Is it the oe clamp?
Did you lube that bolt up? A wet torque will provide more clamping force than intended resulting in an over-torque while using a calibrated tool.
Picture shows a big gap between the clamp and the post. Shouldn’t the clamp be on the frame? I would just use a regular allen key. You are lucky you didn’t crack your frame. This has happened to me with the torque wrench when the allen wasn’t seated all the way into the nut. I think the read on the torque is wrong when it is shallowly inserted.
Why the clamp sideways? Have the slot in the clamp align with the slot in the frame. Then provided torque wrench is ok and used correctly you should be all good.
If it’s like Cannondale you reverse the clamp. Bolt at the front not the back. I thought this was nonsense then cracked a seatpost. Never had an issue when installed correctly.
I am so sorry you are dealing with this.
As a personal aside, this is the kind of problem that makes me want to never work in a shop that deals with this carbon shit. The solution being presented is to ***not*** grease the bolts, which goes against everything I learned working a coop. I get it but it just makes me hate carbon even more.
If it turns out to be something else, I would love to know, because it would help me sleep better knowing that I am not crushing seatposts because I instinctively grease every bolt I touch.
The slits never overlap in situations like this. The geometry changes too much and you get an egg-shaped clamp instead of a circle. Your concern about the thicker part of the seat tube is a key. It will, in fact, support the clamp instead of flexing like the slit side. If it’s still a concern, lubricate the underside of the clamp where it meets the frame. This will help them to slide past each other and tighten more uniformly.
What kind of torque wrench?
Don’t overtighten.
Could bad tolerances be the issue? It kind of looks like the clamp is having to compress too much before grabbing the seat post. And there’s also this from the manual linked in another comment.
https://preview.redd.it/bcwsr2hfh9sg1.jpeg?width=524&format=pjpg&auto=webp&s=021cf136f680dbc7aea74cfbd96ff8dc81b2f62a