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I bought a Trek X-Caliber 9, September last year.

About a month ago it started to do a very annoying sound between the welded junction of the Seat Tube and the Top Tube.

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What I have tried:

  1. Switch the seat post and saddle.
  2. Switch the pedals.

I cannot ride with these noises they truly disrupt my mind.


The creaking only shows up when I sit on the saddle, I replaced the saddle and the seat post but the creaking didn't cease. I think the noise is from that area because I've put my hand in there and felt the creaking.

I have cleaned it several times and even if I lower the seat post the creaking continues.


UPDATE: I still have the issue, I am going to the second Bicycle Repair Shop this weekend, But I think it is the left arm crank who's making those noises. But I will keep you updated! 2021-04-23

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    Clean it well, and look at it closely under a bright light. Then get someone to sit on the bike while you look again. This should open up any cracks to be seen. Also lower the seatpost by a lot and see if the creaking goes away, as a test.
    – Criggie
    Mar 27 at 20:54
  • Is there grease inside the seat tube between it and the post? Is the post long enough, and is the seat post collar tightened to the appropriate torque? When does it make the noise, and how do you know it’s coming from the seat junction? Tracking down the source of a noise can often be a lot of trial and error. What’s your question?
    – Pisco
    Mar 27 at 20:58
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    How long is the seatpost below the clamp? Mar 27 at 21:21
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    You know Trek warranty is the best bar none and they'll sort you out?
    – JoeK
    Mar 27 at 23:12
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    Are you correctly tightening the seatpost clamp?
    – MaplePanda
    Mar 28 at 4:37
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I suspect that your seatpost is graunching inside the frame as the rider's weight moves about while pedalling.

By inserting the post much further than normal, it will apply a different less-worn part of the post to the clamping area of the bike. But you've tried this and the noise continues.

So the next cause is that the frame is slogged out already in the clamping area, because of movement of the seatpost and the leverage afforded by the long unsupported length. You could do the seatpost clamp up tighter, but this is likely to be a short term fix.

Try unclamping the seat post, removing, and then do up the clamp without adjusting it. Then measure the hole with vernier calipers in multiple directions. You want to see the same number in all diagonals. Also feel inside with a finger - it should be flat in-line with the seat tube of the frame, with no detectable curve.

If there's physical damage, you should talk warranty with the seller as soon as possible.

Personally the super-long unsupported seatpost is a recipe for disaster IMO. I've cracked three frames in decades, and bent multiple seatposts by having them too long and/or too little inside the frame.

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    It could be a matter of tolerances, upper limit of the seat tube meeting lower limit of the post.
    – Carel
    Mar 28 at 7:09
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    @Carel could be - another possibility is a crack in the frame due to the excessively long lever-arm of the seat post. I broke my first road bike that way, with a crack under the seatpost clamp.
    – Criggie
    Mar 28 at 7:38
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    I've had noise coming from the saddle-rails where they sit in the cover, usually 4 spots. It may then transmit to the frame. It went away when I sprayed in some Teflon chain lube.
    – Carel
    Mar 29 at 19:08
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Lucky you! A creaking left crank arm is far more common than a creaking seat post, and a lot easier to fix. A mechanic will not be able to see this problem in the stand because it usually only appears under some load. Pushing the crank arm sideways (away/towards the bike) sometimes makes the noise, but not always.

Confirm for yourself by pedaling uphill only with the right side and seeing if it creaks, then only with the left. The loose side will usually creak more than the other.

It can be fixed by tightening the crank bolt to its specified torque, which can vary from 240-521 inch-pounds. The crank arm should be replaced if it's obviously worn, i.e. rounded on the inside instead of square.

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