Carbon seat tube clamp keeps loosening

[jaxpaw]

I've got a Specialized Roubaix and after every ride the seat post clamp is not as snug as it was before the ride. The seat is not dropping but if I lightly tighten the clamp it turns less than an 1/8th of a turn. I'm afraid I might be progressively tightening the clamp too tight and damage the frame over time. I was thinking about trying a little Loctite on the threads and see if that does the trick. Any other thoughts? Thanks, Carl.

 

[lks]

I've got a Specialized Roubaix and after every ride the seat post clamp is not as snug as it was before the ride. The seat is not dropping but if I lightly tighten the clamp it turns less than an 1/8th of a turn. I'm afraid I might be progressively tightening the clamp too tight and damage the frame over time. I was thinking about trying a little Loctite on the threads and see if that does the trick. Any other thoughts? Thanks, Carl.

Well, maybe your hand is just stronger, after gripping the bars during the ride. A torque wrench would tell you if the bolt torque has changed. I would tightened it like you always do before your ride. Then make a little mark on the bolt and clamp at the same point. I take a pin and dip it my car's white touch up paint to do that and make the smallest dot possible. If you bolt is loosening, you will see that the two white dots have moved away from each another.

 

[fauxpas]

Get a marker pen of some sort and put a dot on the top of each side of the clamp nut and bolt. After your ride, check it the dots have moved... <-- someone got in before me...

That will at least establish if the clamp is undoing itself...

If the clamp has not budged, then maybe heat from pressure from your weight allows the post to flex a bit, therefore enabling you to turn another 1/8th.

I only ever revisit the seatpost clamp if I hear it creeking, which is my first clue it may be loose.

 

[John M]

The seat is not dropping ...

If this the case, then it is tight enough.

 

[Rich8P]

Carbon is slippy. Are you using a mounting paste for carbon parts? I seem to remember that you need one.

Don't over tighten it, you'll just get an expensive cracking sound.