Seat post clamp what ain't weak?

[Trevize1138]

My '01 Stumpy's got that Specialized 30.5 (mm? cm?) seat tube and ever since I've had it that part of the bike's been the source of some nasty creaking. Doesn't matter the seat post. I've gone from the stock to a Rock Shox and now a Thud Buster. Tighten the bolt on the seat post clamp and within 10 or 15 miles of dirt it starts creaking and the seat post slowly shimmies its way lower and lower into the seat tube.

Last year I briefly had some replacement seat post clamp I got for $5 or so from The Alt but it only lasted a month before I snapped the bolt on it trying to get it tight enough. Seems like the seat tube and seat post on this bike beggs to be clamped on really tight but the stock clamp is already bending out of shape and I'm always afraid to tighten it too much for fear of snapping another clamp bolt.

Ideas, anyone?

[Kosk]

1. Drink a can of beer
2. While drinking another can of beer, cut the top & bottom of the first can off.
3. Cut the "ring" in half so you have a "sheet" of aluminium.
4. Cut this sheet to size to make a shim.
5. Shim your post in the seat-tube.

If a "full wrap" is too much, cut is down to 3/4,1/2, etc to get it to fit.

Grease inside of the seattube and post lightly, then wipe off (you want a residue, but not too much grease, just to keep the alu seatpost and steel frame from corroding together.)

[Konaboy]

Surly Constrictor should take care of your problem.

[rideharder]

Grease inside of the seattube and post lightly, then wipe off (you want a residue, but not too much grease, just to keep the alu seatpost and steel frame from corroding together.)

make sure you clean it first with simple green or some degreaser as the problem lies in the dirty grease in the seat post.

[flombe]

Make sure the first beer you drink is a light beer if you are a weight weenie....:D

[turbo_kitty]

from what i have found in specilized's archives http://www.specialized.com/bc/SBCBkModel.jsp?arc=2005&spid=20887
and the 2002 is not to different than the 2001 your bike should take a 30.9mm seat post not a 30.5mm. i'm not 100% on this because all you have told us is stumpy and 2001 so maybe a fieldtrip to the LBS and have you seat tube looked at...that sound dirty...anyway that's what i'd do.

[soupboy]

What he said. Nothing is more gooder than the Surly.

Surly Constrictor should take care of your problem.

[Trevize1138]

Hmm ... dirty seat tube smells about right somehow. The stock seat tube didn't last very long as the clamp actually crimped it! I wonder if the constant tightening and crimping of that seat clamp started everything down the wrong path. Then, on top of that, stuff got dirty? I'll try cleaning it and see what that does. :)

[pro1200]

This is one of the problems I tried all last summer to fix on my new hardtail. What finally worked for me was 1)the application of a "friction paste" made by Syntace, and 2)I'm using a quick release clamp so I greased the sliding surfaces of the clamp so more of the clamping force goes into squeezing the post, rather than friction. These two things eliminated the creak. I am also on my third seatpost as it seems they are either too small or deform over time.

[Kosk]

Hmm ... dirty seat tube smells about right somehow. The stock seat tube didn't last very long as the clamp actually crimped it! I wonder if the constant tightening and crimping of that seat clamp started everything down the wrong path. Then, on top of that, stuff got dirty? I'll try cleaning it and see what that does. :)

Likely it'll be worse as your seat slowly sliping down means the post OD is slightly smaller than the seattube ID. Cleaning it will just remove dirt that was helping to take up the void.

The solution is to take up the void between the two diameters. You are already doing this at the clamping point, but this is only a very thing "ring" of contact. As a result the seatpost below the clamp and "wobble" back&forth inside the seat tube. If you add a beer can shim you will increase the length of seattube-to-seatpost contact, reducing/eliminating the wobble. Clean it out and then beer can shim it. I quarantee it'll fix the problem.

[Trevize1138]

Likely it'll be worse as your seat slowly sliping down means the post OD is slightly smaller than the seattube ID. Cleaning it will just remove dirt that was helping to take up the void.

The solution is to take up the void between the two diameters. You are already doing this at the clamping point, but this is only a very thing "ring" of contact. As a result the seatpost below the clamp and "wobble" back&forth inside the seat tube. If you add a beer can shim you will increase the length of seattube-to-seatpost contact, reducing/eliminating the wobble. Clean it out and then beer can shim it. I quarantee it'll fix the problem.

I agree. However, I'm using a Coke can shim. Beer is meant to be drunk from a bottle. ;)

[Kosk]

I'm using a Coke can shim. Beer is meant to be drunk from a bottle. ;)

Pass me another can of pig's eye, coke-head.

[SLP Punk]

1. Drink a can of beer
2. While drinking another can of beer, cut the top & bottom of the first can off.
3. Cut the "ring" in half so you have a "sheet" of aluminium.
4. Cut this sheet to size to make a shim.
5. Shim your post in the seat-tube.

If a "full wrap" is too much, cut is down to 3/4,1/2, etc to get it to fit.

Grease inside of the seattube and post lightly, then wipe off (you want a residue, but not too much grease, just to keep the alu seatpost and steel frame from corroding together.)

Sierra Mist works too! My Crosscheck has a little green tab sticking out of the seattube. Works great!

[Trevize1138]

Pass me another can of pig's eye, coke-head.

By the way, after two laps at Leb yesterday my post hadn't moved a millimeter and was nice and quiet :). Thanks for the tip, Pete!