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#31
10-13-2017, 08:09 AM
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#32
10-13-2017, 10:09 AM
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That looks like a Thomson post. They are sometimes a little undersized. Also, they have very little material in the column and will be crushed slightly when you crank the seatclamp down, going nowhere with the slipping problem.
At this point you should get a new post or try a different seatpost. Measure the diameter with a pair of verniers if you can and try to get a post fatter than the current one. A small difference in diameter should be all you need.
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#34
10-13-2017, 10:36 AM
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Two quick things -
First is that your post is toast. You need to replace it with a new post that is not a thomson. Second - can you post a photo taken from the rear showing the binder area and the slot? dave
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#35
10-13-2017, 10:48 AM
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Wow thanks for chiming in fellas. So it's not a Thomson. Some cheapo a buddy had in his parts bin. Not sure if that's any consolation unfortunately
Here are pics David. See anything odd?   Sent from my iPhone using Tapatalk
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#36
10-13-2017, 10:50 AM
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The binder looks good.
Do you have any calipers to measure the diameter of that post? dave
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#37
10-13-2017, 10:52 AM
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If you don't mind sharing your expertise, what Nm would you be tightening this to?
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#39
10-13-2017, 11:01 AM
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I'd find a friend with some calipers and see what size that post actually is. dave
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#40
10-13-2017, 11:39 AM
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Here's what I'd do -
With the post in place in the frame put a sharpie mark at the top of the seat lug point. Now remove the post and measure the O.D. of the post just below the head up top and make a note of it. Next measure the O.D. about 1" below the sharpie mark and make a note of that. Both should be in the 27.15 - 27.17 range for a proper fit. If it's right up top but small in the clamped area the post is all done. It's been compressed. The post looks like it's a LaPrade which were made out of butter and necking down was common. Without those numbers you are shooting in the dark. The grooves that were made in this post no doubt didn't help. You may have made the effective OD very slightly larger but you also cut the surface area where the frame and post meet by a large percentage. For this reason alone, even if the post is the right size, I'd toss it and put a new post in place.....and I'd measure it before installing it. dave
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#41
10-13-2017, 11:50 AM
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Since you don't have a way to measure at the moment... that would be the best way to figure out what is going on with this seatpost. Are you sure this one is 27.2 (at least what it says on the post)? Have you tried using carbon/assembly paste with this seat post? Can you swap a seat post from another bike to see if it does the same thing?
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#42
10-13-2017, 06:54 PM
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So prior to last couple of posts/suggestions I went with removing excess grease, added carbon paste and after 2hr ride no movement.
I'm certain seatpost is 27.2. But now I'm thinking I should be in market for replacement.... Also interesting to hear regards towards Thomson, always thought durability was their biggest draw. Thanks again for Info DK and others
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#44
10-13-2017, 08:31 PM
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Cool - FWIW.....what a post is stamped and what it is are rarely the same. gt your hands on some calipers and you'll know the actual size. dave
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#45
10-13-2017, 09:49 PM
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Azrider, another frame builder chiming in, how long is the binder slot? I couldn't tell from your picture. If it is not longer than more than an inch it can be too short and won't hold your seatpost.
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