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Old 07-18-07, 11:45 AM   #1
ron m
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Seat post won't cooperate

This season I've had this nagging problem with my seat post. It seems no matter how tight I make the collar, the seat post slides down during my ride. Last night I even de-biked during my ride (at about the 10 mile mark) to raise the post and by the end of the ride (25 miles) it found it's way down again. Any helpful suggestions? Thanks in advance.
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Old 07-18-07, 11:50 AM   #2
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1. your seat post is too small for the bike
2. the bolt that connects the collar is too long (can't screw far enough and so it is loose).
I can't think of what else it could be. The solution to #1 is obvious, if it is #2 then you can either get a longer bolt or you can put a shim or washer on the bolt- on the outside of the collar- and that will effectually lengthen the bolt and make it clamp tighter.
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Old 07-18-07, 12:57 PM   #3
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Quote:
Originally Posted by ron m View Post
This season I've had this nagging problem with my seat post. It seems no matter how tight I make the collar, the seat post slides down during my ride. Last night I even de-biked during my ride (at about the 10 mile mark) to raise the post and by the end of the ride (25 miles) it found it's way down again. Any helpful suggestions? Thanks in advance.
no, i don't believe it is what was mentioned above...don't get me wrong, they are viable answers.

i had the same issues with my seat post and similar issues with my front derailleur. i am FAR from an incompetent mechanic...so i know it is not my fault.

for my thomson post into a steel frame i used some permatex gasket sealing glue that never really dries but gets sort of tacky. that helped for many months. however, the other day it actually slipped after i made an adjustment to the height. i guess i broke the "bond".

next on my list to try if it gives me any more probs is something like a little 3M tacky spray "glue" stuff. or possibly a weak thread locking agent (but i don't think this would "set" up...not sure)

anyhow, just know you're not alone.

as far as my FD goes, i have to use these stupid plastic spacers which seems like they are Teflon impregnated

i've had continual problems with the FD and it is not really my fault. i've done nothing wrong or incorrectly. incredibly annoying...
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Old 07-18-07, 01:14 PM   #4
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Some bikes come with shims for the seat post. If so, make sure that the slot in the shim is lines up with the slot in your seat tube. This caused me some headaches on my bike before I discovered it. I didn't even know I had a shim before I discovered this issue on mine. Mine apparently got twisted while making height or position adjustments at some point.

These others are just to make sure you've checked the obvious...

From what you have written, I assume you have tightened the nut up a half turn or so before clamping it down... (if you have a quick release)

Also, is the opening of your clamp aligned with the slot in your seat tube? It should be...
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Old 07-18-07, 02:16 PM   #5
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That is often a problem with carbon posts in carbon frames (you haven't indicated the material). A little roughing up the post (below the insertion level) with some fine grit sandpaper will solve the slippage.
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Old 07-18-07, 03:05 PM   #6
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More information

Sorry for the incomplete post. I ride a 2002 Lemond Buenos Aires, steel frame with a carbon seat post, stock. The fastener isn't a quick release and requires an Allen wrench to tighten. Thanks for all the suggestions. I'll report back tomorrow.
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Old 07-18-07, 05:16 PM   #7
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Originally Posted by ron m View Post
Sorry for the incomplete post. I ride a 2002 Lemond Buenos Aires, steel frame with a carbon seat post, stock. The fastener isn't a quick release and requires an Allen wrench to tighten. Thanks for all the suggestions. I'll report back tomorrow.
I'm having the same problem with my Steelman, and an Easton Carbon seatpost. Already snapped a seat collar bolt, after tightening it, and then trying to loosen it to take it out... I've decided to just switch out to an aluminum seatpost, it frustrated me that much... I never seem to have a problem with those!
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Old 07-18-07, 05:28 PM   #8
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This bike uses a seat collar, yes? I'm guessing that it is not a brazed on seat clamp, as many builders don't use these anymore, other than custom builders. I suppose you could try a new clamp, it's possible that the old one is stretched. And don't use grease on a carbon post. There should be no chance of a corrosive reaction like steel against aluminum.
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Old 07-18-07, 05:30 PM   #9
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ron m,

You might find something here....................

http://www.loosescrews.com/index.cgi...d=593620920616


Good luck.
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Old 07-19-07, 09:11 AM   #10
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I had this issue for a long time - 0.5mm to 1mm of slippage every km! Carbon post, alu frame. Clyde, 300 lbs.

Tightening it did not do much. At one point, I noticed the edge of the slot in the frame had worn a groove in my seatpost! I sanded it smooth (only the upper decorative layer was damaged - I caught it in time), added a soda can shim (due to the sanding making the post smaller) and bought a new clamp (bolt, instead of my old quickrelease), which I tightened down REAL right. As in 3-4 turns beyond "dangeous-seeming tight".

It still slipped!

However, the soda can shim sort of crumpled due to the slippage and this caused enough of an obstruction to stop it from slipping after a cm. I find the height pretty comfortable, so I am not going to mess with it anymore until it becomes a problem again
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