Recurring creak on integrated Chinese aero seatpost frame — tolerance issue?

[giorgiobuccio]

Hi everyone,

I’m looking for some advice about a recurring seatpost/seat tube creaking issue on a high-end Chinese aero carbon frame with an integrated seatpost/clamp system

Summary:

* The bike was perfectly silent for the first few months.
* About two months ago, a creaking/cracking noise started from the seatpost area.
* The noise slowly got worse over time.
* The seatpost does not slip down and saddle height remains stable.
* I tried cleaning everything several times.
* I tried carbon assembly paste.
* I tried different torque values.
* I tried different wedges/clamps.
* I also tried another standard seatpost.
* The noise sometimes improves temporarily, but then comes back.
* The old smooth seatpost, used for months, shows no clear damage, no deep scratches and no obvious wear marks.
* The inside of the seat tube also does not show any obvious crack or major damage.
* A new machined/thickened seatpost was supplied and installed.
* With the new seatpost, the bike was perfect for the first long ride: about 4 hours, including rough roads, completely silent.
* The following day I noticed a very light noise again.
* On the third ride, the noise became constant again, although not as loud as before.

One strange detail: today the noise changes depending on my riding position. If I remove my hands from the handlebar, the noise almost disappears. With normal riding position and load, it comes back.

At this point I suspect a small tolerance/interface issue between the frame, seatpost and wedge/clamp area under riding load, but I’m not sure.

At this point, what would you do? Keep trying to fix it, or ask the manufacturer for a warranty solution?

I’m attaching a few photos.

PS: * In the photos, the wedge/clamp may look damaged, but it is only grease/dirt. The part itself is in good condition.
* I also tried cleaning the wedge/clamp, using grease, using threadlocker, removing the grease, and replacing the wedge/clamp with a new one, but nothing changed.

[BeR]

Sometimes, even if your are sure that the noise comes from the saddle, it is not the case. Are you able to replicate the noise only with your hands by moving the seatpost front and rear (without stand on the bike) ?

Have you checked your saddle rails ?

Have you tried a different carbon paste ?

[giorgiobuccio]

I've honestly tried everything at this point. 

I've tested three different seatposts, including one with additional carbon reinforcement. I've also tried several types of carbon assembly paste, both on my own and together with my mechanic, always tightening everything with a torque wrench according to the specifications.

I've changed the clamps as well, trying two different clamp sets, but the noise is still there.

I'm quite confident the issue is coming from the seatpost area because the moment I get out of the saddle and ride standing up, the noise disappears completely. My mechanic is convinced it's the seatpost too.

Another clue is that sometimes, if I tighten the seatpost clamp slightly more, the noise disappears. It may stay quiet for an hour or so, but after a few bumps in the road, the creaking gradually comes back.

Unfortunately, this has been going on for months and it's becoming extremely frustrating because neither I nor my mechanic have been able to find a permanent solution. The bike is only a few months old, and at this point the only option I can think of is to request a frame replacement under warranty. I just hope the claim is accepted, because honestly I don't know what else is left to try.

[Leo.D]

Integrated aero seatposts can develop creaks from two places that people tend to overlook:
One is the wedge clamp itself. Some of these frames use a two-piece wedge system inside the seat tube, where the bolt pulls a lower wedge up against an upper wedge, expanding them outward to press against the tube wall. If those wedges are aluminum and the inside of the seat tube is raw carbon with no anti-seize, you'll get stick-slip between the metal and carbon that sounds exactly like a seatpost creak. Pull the wedge out, clean the contact surfaces, and apply a thin film of anti-seize (not carbon paste — opposite job here) between the wedge faces.

The second possibility is the carbon sleeve bonded inside the seat tube (the bore the seatpost actually slides into) has a small area of incomplete bonding. Under load, it flexes microscopically against the outer tube wall. That's harder to confirm without a borescope, but a telltale sign is that the noise changes with temperature and even worse on cold mornings when materials contract. If this is the case, it's a warranty conversation with the manufacturer.