JimOfOakCreek

I have a great frame, a Soma Smoothie ES. One fault I don't like about it is the built-in seat post clamp.

My seat post keeps slipping downward after long rides. I keep tightening it. Is there a danger of tearing the welds on the threaded lugs by over tightening?

I am a klidesdale at 6'5" - 240LBS.

Metzinger

Yes, you could wreck the clamp.
I have a similar problem on an old Italian bike. The ears are now touching. A longer seatpost seems to jam in the tube better.
You could try using an assembly paste in place of grease on the post.

prathmann

There shouldn't be a need for periodic retightening. I wonder if your seatpost is slightly too small for your frame. Have you tried a post that's one size up in diameter to see if it might fit? Might also try a shim together with your current post (soda cans usually work well as shim material).

HillRider

If (big if) your seat tube projects above the top tube enough to allow you to fit a seatpost clamping collar you could grind off the ears and replace them with the collar and then you can tighten it to your heart's (and seatpost's) content.

Other possiblities are that your seatpost is the wrong size or is at the minimum diameter or your seat tube is too large so you can't get a proper fit. You might try a different seatpost or go up one size.

Metzinger

^Good idea...

... and he could grind off those rack mounts while he's at it.


(jkng)

ultraman6970

+1 in the assembly paste, what you can do is to use a sleeve made of a coke can, the material is pretty thin.

The other solution and im looking in to this because of a noisy seatpost is to use liquid electrical tape inside of the seatpost.

Good luck.

Al Criner

Have a shop check the seat tube to check the sizing, this will at least tell you if the seat tube is off a little. Then you can make the proper decision regarding a new seat post or shim.

Make sure the bolt is greased, so you get proper feel for torque when you tighten it. A torque wrench will tell you have it torqued properly (meaning you want to avoid too much as well as too little). It shouldn't take a hell of a lot if the post and seat tube are a proper match. You are obviously better off with a shim than a jacked-up clamp.

GreenRiver

I also have a Soma Smoothie ES. I have to tighten the binder bolt to the max "hand tight" (one hand) to keep the post from slipping. As a result, the eyelets/lugs are pinched together. I do use thread lube on the bolt. The welds appear to be intact. The Thomson seatpost was provided by the shop that did the build for me (the post is the right size) Do I have a problem here? Any thoughts/ideas will be appreciated. Thx.