[onepivot]

OK, this has to be a problem with some Clydes. My seatpost sinks @ 1/4-1/2" on each 90 minute ride. I'm riding a Ventana Pantera with a Thomson post so it's not like I've got some cheap stuff here.

I've tried different clamps (quick release and regular) and also tried an Easton carbon post with the same result. I have always used a thin film of grease on my seatposts and I even cleaned that off in hopes of fixing this problem. I've owned three other bikes in the last four years and this is the first time I've had this trouble. I ride fairly tame XC type stuff with only an occasional one foot drop so I'm not too hard on my bike exccept for my 6'3" 240 lb. bulk.

So.......what's the fix (besides getting my A$$ off the seat more often) Is there a type or brand of seat clamp that holds tighter than others?

Thanks!!!

Russ

 

[Fattirewilly]

OK, this has to be a problem with some Clydes. My seatpost sinks @ 1/4-1/2" on each 90 minute ride. I'm riding a Ventana Pantera with a Thomson post so it's not like I've got some cheap stuff here.

I've tried different clamps (quick release and regular) and also tried an Easton carbon post with the same result. I have always used a thin film of grease on my seatposts and I even cleaned that off in hopes of fixing this problem. I've owned three other bikes in the last four years and this is the first time I've had this trouble. I ride fairly tame XC type stuff with only an occasional one foot drop so I'm not too hard on my bike exccept for my 6'3" 240 lb. bulk.

So.......what's the fix (besides getting my A$$ off the seat more often) Is there a type or brand of seat clamp that holds tighter than others?

Thanks!!!

Russ

I assume the clamp bolt is on the side the seat tube with the "slot", if not, try that. I've had better luck with seat claps that have a larger allen bolt head, which allow a larger wrench, more torque and less stripping. I've also read somewhere that applying chalk (or dirt in pinch) to the seat post will also help.

 

[AL29er]

Dirt will do in a pinch to create some interference and friction. Be sure to use powder not rocky sand.

Sounds like it may just be a worst case tolerance stack up (post on the small side and hole on the large side of acceptable). I would swap out to a reputable seat binder, ditch the qr, and tighten the shizzle out of it. I had to do this on a hardtail that had a settling seatpost.

 

[NoDunut4U]

Is there a type or brand of seat clamp that holds tighter than others?

Surly Constrictor..... It's all I use on any of my rides.

 

[uber-stupid]

Dirt will do in a pinch... but not, I wouldn't think, on a carbon fiber post. Anything that can score the fiber will help it to go down a lot faster than 1/2", if you know what I mean...

The thin coat of grease is a good idea, try wiping some of it off if you're sinking. The clamp on the slotted side is good advice.

If you're still having issues, maybe try shimming the post with a piece of coke can or something... just something to take up the space around the post so the seat tube can get a better grip.

But don't put dirt in around a carbon post.

 

[Fattirewilly]

But don't put dirt in around a carbon post.

Don't put grease on a carbon post either.

 

[farley325]

A friend of mine ad touble with his Thomson post after a year or so because the horizontal ridges wore down after adjusting the seat height so often. Consequently the 27.2mm post diameter was slighly worn downa nd now the post slides on him. He's around 200lbs. Watch out for that on your Thomson, if it keeps sliding you may consider a different post as you ridges may be worn down.

 

[preparation_h]

A friend of mine ad touble with his Thomson post after a year or so because the horizontal ridges wore down after adjusting the seat height so often. Consequently the 27.2mm post diameter was slighly worn downa nd now the post slides on him. He's around 200lbs. Watch out for that on your Thomson, if it keeps sliding you may consider a different post as you ridges may be worn down.

I had this same problem...it's the Seatpost.....Swore I'd never buy another thomson.....I bought another thomson. These seatposts' will "dent" while clamping down on them. this in turn will cause slippage.

 

[banks]

I had this same problem...it's the Seatpost.....Swore I'd never buy another thomson.....I bought another thomson. These seatposts' will "dent" while clamping down on them. this in turn will cause slippage.

PH,
you said that right!!!! The posts are too thin, even with 150 lb rider from what i have seen on the Klein Palomino.

You can also use valve lapping compound in the seat tube to keep the post from slipping if it was not a T'son post.

Get a Salsa/Ritchey/Bontrager post and go with gusto!!.

Scoty

 

[uber-stupid]

...Now that I think about it, I seem to remember hearing a bit of advice about putting paper under the clamp of anything you're clamping to a cf handlebar. You might be able to get away with wrapping a layer of brown bag paper around your post (or inserting it into the tube) and then clamping down. The paper is softer, so it should grab whatever texture is left on the post, as well as keeping your seat clamp from scoring the post up. Basically a textured shim.

 

[Scottay5150]

I have your anwser...

Have you used a Salsa quick release clamp combo. If the post is not bent the clamp is not strong enough ..the Salsa is designed differently should work for you ...it did for me ( i am 260)

Scott

 

[Kneedragger]

I actually had a similar problem on my Fisher joshua f-4. It got so bad, that the frame that recieves the seat post got hogged out. It was becoming somewhat oval. Me and a tech at my local LBS, cut a wider slot out of the frame material to allow for a tighter fit, and he wrenched the crap out of my QR. Now I don't dare move the seat post height because I am not sure I can get it to hold again.

 

[willtsmith_nwi]

aluminum can ...

I've read that cutting up an aluminum can and using it as a shim will work.

 

[malariavalley]

tap it

drill your tube at the spot where you want your post to seat. insert a pop rivit and problem solved. no one will ever notice.