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Loosening seat post at seat clamp?

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Loosening seat post at seat clamp?

Old 05-23-19, 01:09 PM
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tiger1964
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Loosening seat post at seat clamp?

Again, something I have never experienced in all my years on a bike. Yesterday, coming home the seat felt odd, when I arrived at home the seat was flopping around in the seat post clamp (Avocet micro-adjusting seat post on the Palo Alto), at least the bolts did not fall out. Never had that on any bike with any post/clamp, plus I've had this bike 20 years and I've been riding it a lot in the past 2. So, I tightened it up until I worried that I'd snap off a bolt. Rode again today, and before I got home, it was loose again, 18 miles since the last tightening. Really? Do I need thread locker on everything? I don't think my pedaling style has changed. Anyone else experience this?

After the odd hub bearings on the Avocet hubs (finally got those replaced) and the recent spindle-taper woes on the Avocet cranks (still worried about that), I wonder if I should de-Avocet the bike.
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Old 05-23-19, 01:15 PM
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Sometimes the clamp parts can become bent, usually by overtightening. Once they are bent, when you tighten the bolt, the never grab the rails right again. Further efforts to tighten can inadvertently overtighten further, exacerbating the problem. I imagine it might be possible to take it apart and bend them back, but probably best just to replace the seatpost.
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Old 05-23-19, 01:40 PM
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Very good feedback! Might not be applicable this time --

A quick visual inspection -- without disassembly -- shows no obvious bending. The contact surfaces for the upper and lower halves of the clamp, where it contacts the seat rails, is about 1.5" long on each side. Certainly no upper-to-lower-half contact, visible space on all sides so the "gripping" is against the seat rail (which does not look deformed).

For now, would like to keep it in service but the last seven words of your answer are the most logical.

Originally Posted by arimajol View Post
Sometimes the clamp parts can become bent, usually by overtightening. Once they are bent, when you tighten the bolt, the never grab the rails right again. Further efforts to tighten can inadvertently overtighten further, exacerbating the problem. I imagine it might be possible to take it apart and bend them back, but probably best just to replace the seatpost.
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Old 05-23-19, 01:49 PM
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Avocet post? My advice? Ditch it before it breaks on a ride. I broke a bolt on a year old Avocet many years ago on a ride. 50 miles from home. Turned taht ride into an epic. Same post, happened again 5 years later. 2008 I had another Avocet post in my custom break; this time though the clamp and the seat simply fell off.

Suck it up, buy a 2-bolt Nitto, Thompson or used SunTour and don't look back. (Best Avocet posts? The ones taken off and placed tn the spare parts box before they broke.)

Ben
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Old 06-18-19, 01:29 PM
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Oddly, after those two instances, it has not occurred again. Make no sense to me.
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Old 07-12-19, 12:15 PM
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And... it's back. Six or so weeks with no trouble, today it came loose all at once -- it was fine yesterday. I'll retighten but shop for a replacement.
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Old 07-12-19, 02:15 PM
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Examine the clamping pieces and surfaces really close to see if something is slowly cracking on you.
I'm suspecting that something around the clamping areas is flexing and moving around enough to cause the bolts to loosen up whole you ride.
Just like many failing crank arms, the crank might be modtly invisible in the surface and the cracks, if any might be propagating under the face of the aluminum.
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Old 07-12-19, 10:28 PM
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I've been experiencing this same issue with two separate Campy Super Record one-bolt posts. Two different bikes. I even stripped out the threads in the upper cradle of one bike while attempting to re-tighten it, putting me in the market for a pretty expensive replacement head. This one has a stainless helicoil insert (later model cradle) and I cranked it on pretty good. So far, it's holding.

The other? Still slipping, but only on rides where I spend a lot of time climbing in my saddle. Perhaps my weight and push are more than what the setup is normally used to?

I seem to recall a thread talking about the iffiness of those Avocet one-bolt posts, but can't remember any specifics of why they got a bad rap. I've never had an issue with my Campy posts before (either 1 or 2 bolt designs), and haven't heard of others who have, either. Of course, that's not to say others haven't.

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Old 07-13-19, 03:22 PM
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Originally Posted by Chombi1 View Post
Examine the clamping pieces and surfaces really close to see if something is slowly cracking on you.
Good idea, and I examined; no cracks that I can see, A moot point, however, because...

Originally Posted by Drillium Dude View Post
one-bolt posts
... well, the Avocet was once a two-bolt post, and is now a one-bolt post. That's because, one the way home, a bolt fell out and is gone. OK, those could be replaced, but the saddle-shaped nut it fits into is also gone, I'd had to fabricate a replacement by hand -- why? Well, the only other bike I have with a micro-adjusting post is the Falcon that was gifted to me and I converted to an upright-bars errands bike that I never ride, so I can steal the part. Amazingly, it's also a 27.2 according to my micrometer, so I can swap it out. Even more so, as I move everything over to the Masi frame (shortly), that is also 27.2 so I can take time to locate a decent Campy post.
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Old 07-14-19, 10:21 AM
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Originally Posted by tiger1964 View Post
Well, the only other bike I have with a micro-adjusting post is the Falcon that was gifted to me and I converted to an upright-bars errands bike that I never ride, so I can steal the part. Amazingly, it's also a 27.2 according to my micrometer,
Done, it fits. Snug, but I had to buff down the replacement post w/400-grit to remove scratches anyway, and I ran a brake cylinder hone down the seat tube to clean that up... it went in well enough and a 100-foot "test ride" suggests I'm temporarily good to go. Still need to locate a decent Campy post to return this no-name post to the Falcon.
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