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bikerbert
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I've got an 05 Trance, and my seatpost keeps slipping. I know the size is right (30.9), but it keeps slipping. I've tried a QR and a regular collar, but no luck.

It is wreaking havoc with my riding/racing, because I have to constantly adjust the saddle on the fly. I know it is slipping because I can feel more fatigue in my quads, and when I take the measurements of the seat post ride, they are different.

I've got a set back Thompson Elite. This also happened with a RaceFace Deus post as well.

Any help I can get would be great!

THANKS!!!
 

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Fart smeller
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bikerbert said:
I've got an 05 Trance, and my seatpost keeps slipping. I know the size is right (30.9), but it keeps slipping. I've tried a QR and a regular collar, but no luck.

It is wreaking havoc with my riding/racing, because I have to constantly adjust the saddle on the fly. I know it is slipping because I can feel more fatigue in my quads, and when I take the measurements of the seat post ride, they are different.

I've got a set back Thompson Elite. This also happened with a RaceFace Deus post as well.

Any help I can get would be great!

THANKS!!!
I had the same problem, and tried the same "solutions" you did, with no results.

Finally I went to a machine shop & ordered a collar that sits on top of the other collar and I tightened the sh!t out of it. It's a heavy solution, but the only one that's worked for me.

I can post pics if you need to see it.

fp
 

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Have you tried friction paste?

After you clean it, why don't you try some carbon assembly compound (FSA, Tacx, etc). They are designed to increase friction and might give you that extra oomph needed to keep your post from slipping.

-James
 

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I've had the same issue. I was going to try the carbon assembly compounds but before I could I was so frustrated mid-ride that I rubbed some dirt/dust on it and it hasnt slipped since.
 

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+1 on the surly constrictor. It did the trick for me. My post and seattube were both clean, I had just a little lube (phil's grease). But, my thompson and my gravity dropper would slip.

Put the constrictor on, and that was the end of that. Great product.
 

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use carbon "grease"

There is a friction grease used for carbon/carbon interfaces. I use it for all carbon posts in carbon frames (where normally you can't use grease).

It is basically grease w/ some sort of abrasive in it. It is usually red and one brand is made by Tacx and is called Dynamic Assembly Compound for Carbon.

Put this stuff on your post and in the frame and slipping will be gone guaranteed.

Also works killer for bar/stem interface.
 

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Do you know anyone who works in a machine shop who has the tools to measure your seat tube inner diameter or maybe ask your lbs if they can, although it's very unlikely they would make an accurate measurement. I've been having the same trouble with 1 of my bikes and i'm starting to wonder if it's an industry problem. Here's my analysis thread on the general discussion forum http://forums.mtbr.com/showthread.php?t=428118.

With the collar loose if your seat post slides in then it's likely the seat tube ID is to large or the seat post diameter is to small, if you're using a better brand name seat post then the tube is likely reamed oversize. For a reamed hole of this size anything that is 0.021mm (.001") over its nominal size is then out of specification. If you do a title search for the term seat post you'll find quite a few posts dealing with this problem, here's one on the iron horse forum where the post was 0.2mm oversized and iron horse warranted the claim and sent a new bike.

Not sure about any of the other Giant bikes but my 2004 XTC has a seat post shim that brings the seat post down to a 27.2mm diameter. The reason shims work well is because they appear to have a tighter ID that holds the post snug and they also have a lip so they cannot slide down the seat tube no matter what size the tube is reamed to.
 

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I've had the same problem with several bikes. Cleaning and putting grease on sometimes helps. Not putting any grease on will result in creaking.

Another cheap solution: put some electrical tape just above where the seatpost enters the frame. It sounds weird, but this is just enough to prevent the post from slipping.

But really a frame in which the seatpost keeps sleeping should have been exchanged under warranty. A bit too late for your 05 though...
 

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Ritchey Resin

. It's some kind of resin. I have an aluminum Thompson on my fixie and it was sliding when I first got it. I haven't seen the stuff but a frame builder put it on my post and it hasn't slipped again. Maybe call or email to Ritchey Logic.
 
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