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Time for a new seat post?

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Time for a new seat post?

Old 09-11-08, 08:01 AM
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Time for a new seat post?

The AL seat post on my 1993 mtb has developed a ridge along the back side, running vertically along its length.

It's probably your standard moderately long AL post, might be around 300mm long and weigh about 300g; this is a "Marin Lite" seat post, original equipment, it saw about 4 summers of moderate XC off road use in the mid 90s and has been my semi-abused urban commuter since 2005, I weigh 200-220 lbs., but I'm careful about unloading over big bumps (when I see them in time).

would you say seat post failure is imminent? Is this a seam opening? How much more stress does wrapping a 7-10 pound chain and lock around the post cause? (I do this maybe 30% of the time)
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Old 09-11-08, 08:21 AM
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Umm....make that two ridges...a shorter one running parallel to the longer one.
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Old 09-11-08, 01:54 PM
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Any kind of metal changing shape on a seatpost, especially without an obvious cause, would worry me. Replacement seatposts are cheap -- I'd go for one.
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Old 09-11-08, 02:17 PM
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You're probably right. I've been having trouble tightening it down recently (it keeps slipping - I thought it was cause I put a new clamp bolt in and re-greased the post while I was at it), which makes me think that second ridge is a new one, and the shape is getting out of round....gulp! Hope i make it home ok tonight.

I might have replaced it already, except I have one of those anti-theft chains around the rails so I gotta break out the chain tool...just being lazy. Not even sure what size it is......26.8, I think
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Old 09-11-08, 03:41 PM
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Seatposts are not made of seamed tubing so you are probably seeing deformation caused by the clamp.

Odds are good that nothing will happen but I agree with Mondoman; replacements are cheap so why take a chance.
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Old 09-11-08, 08:49 PM
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Originally Posted by rmfnla View Post
Seatposts are not made of seamed tubing so you are probably seeing deformation caused by the clamp.

Odds are good that nothing will happen but I agree with Mondoman; replacements are cheap so why take a chance.
I pulled it tonight and there are a few more lines I hadn't seen...when reinserting it has the usual snugness and resistance until you get to the area where I clamp and then it is REALLY loose....it must be squished there.

All of this sealed the deal..I ordered a new one; though I may ride it till that arrives.

I went through Harris online - they usually get me parts in about 2 business days, which is fantastic. I also had few (as in none) other choices for my size needed - 26.4mm and 350mm long. The original is only 320, but I had it extended to just beyond the minimum line (on the safer side by about 2-3mm). So I feel safer with the extra 30mm.

btw, the post is visibly labeled "Marin Lite" near the seat clamp, but is branded a Kalloy on the portion that stays hidden in the frame! The seat rail clamp basically is identical to a Performance (Forte) Kalloy rebrand post I got for my road bike.
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Old 09-12-08, 05:46 AM
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What...No photos?

Didn't happen...
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Old 09-12-08, 07:45 AM
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I meant to snap a pic last night, but I popped the old post back in to ride in today - I will pull and photograph this weekend - no way I'm riding it anymore, it slipped a good 4 cm this am...my knees are killing me but I'm riding it home that way....I dare not raise and snug it up again....I'm sure it's pretty close to giving up the ghost at this point.


the ridges are very visible, it would be good to post for others to help avoid seat post catastrophes.
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Old 09-15-08, 06:29 PM
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Got the new post from Harris Cyclery today - not too shabby!

here's some pics of the old one - yow!

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Old 09-15-08, 06:33 PM
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and some more





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Old 09-16-08, 07:30 AM
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Hmm...new post is slipping a bit too. I may have overdone it withe the grease, though. I usually do, and get a little slipping at first which disappears eventually...as opposed to the old one, which kept getting worse.
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