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Seat Binding Bolt question

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Seat Binding Bolt question

Old 09-18-09, 09:10 AM
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aroundoz
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Seat Binding Bolt question

I love my Thorn Sherpa and it seems pretty well thought out except for the seat binding bolt set up.

Ugly I can live with but I just wouldn't trust it on a long tour or if my post started slipping and I had to really tighten it. The weld seems barely adequate. Most frames w/ an integrated clamp usually reinforce it but Thorn does not, at least on this model. It seems like the bolt is bending as the opposite sides come together.

I am thinking about either having it reinforced or removing it and installing a clamp. Is this possible, preferably the latter?
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Old 09-18-09, 09:14 AM
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Al Criner
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Is it just me, or does that look like it has been over-tightened?
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Old 09-18-09, 09:17 AM
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I agree but... it hasn't and that's my concern. It doesnt take much for it to look like the bolt is bending. I gingerly tightened just enough so it doesnt slip. No leveraging just my 3 in 1 allen.
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Old 09-18-09, 09:56 AM
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Al Criner
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Wow. I assume you have verified that your seatpost is the right size?
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Old 09-18-09, 10:39 AM
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Definitely the right size.
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Old 09-18-09, 09:23 PM
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It's hard to believe the seat post really is the proper one for the bike. If you are absolutely sure...

I'd ignore it, carrying a spare bolt with me. Breaking the binder itself is extremely unlikely; it's the bolt itself that is under the real stress. The welding on the boss looks perfectly adequate to me.

If I really wanted to replace it, a braze-on collar like this one from NOVA cycle supply is cheap, easy to install, and bomb proof.

And yes, it is certainly possible to grind off the original binder and replace it with the cheap, ugly, utterly cheesy collars you see on cheap, ugly, utterly cheesy bicycles. Just make sure the collar diameter you need is available -- Quality Bicycle Parts is a good place to look for this sort of thing.
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Old 09-23-09, 03:23 PM
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Trek used a similar design on the 610 from 1984. Mine had one of the ears break off after about a year. Trek repaired it under warranty, but it still shows the same narrowing. I use a thin brass shim between teh seat lug and the post to take up the excess space -- .003" brass.
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Old 09-23-09, 06:36 PM
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Have you shared your concern with the Thorn forks, or their active online forum crowd, or raised it on the touring forum here? Seems like a mistake they would be unlikely to make.

Anyone ever use one of those hose clamps as an in-field repair. I have four of them holding on the beams on my trimaran, and they seem bombproof, just something you could carry with you for peace of mind. They can come in handy for a number of repairs.
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Old 09-23-09, 08:49 PM
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Originally Posted by Six jours View Post
It's hard to believe the seat post really is the proper one for the bike. If you are absolutely sure...

I'd ignore it, carrying a spare bolt with me. Breaking the binder itself is extremely unlikely; it's the bolt itself that is under the real stress. The welding on the boss looks perfectly adequate to me.

If I really wanted to replace it, a braze-on collar like this one from NOVA cycle supply is cheap, easy to install, and bomb proof.

And yes, it is certainly possible to grind off the original binder and replace it with the cheap, ugly, utterly cheesy collars you see on cheap, ugly, utterly cheesy bicycles. Just make sure the collar diameter you need is available -- Quality Bicycle Parts is a good place to look for this sort of thing.
That one from Nova most likely won't work. Those are designed to slide over the tube, not the lug, and then brazed in.
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Old 09-23-09, 08:51 PM
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Never mind. I just looked at the picture again. Yup, the braze on clamp from Nova would work.
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