Seatpost binder bolt unusual
Has anyone ever seen this type of seatpost binder bolt? Can a different more standard one be used here ? There is no slit in the seat tube that can be clamped down on.Thanks in advance
https://cimg9.ibsrv.net/gimg/bikefor...362b212202.jpg https://cimg4.ibsrv.net/gimg/bikefor...b8a3d851e1.jpg |
Don't use that with a carbon post. Obviously.
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Not unusual, notched side goes against the seat tube.
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Originally Posted by Crankycrank
(Post 22604664)
Not unusual, notched side goes against the seat tube.
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Originally Posted by Kars
(Post 22604698)
does it clamp as well as a standard one?
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There are usually more than one reason why a design isn't used commonly. In this case the lesser ability to hold the post in place, compared to the usual slotted clamp design, is likely a big reason. Just look at the surface contact area of this design and look at a common slotted clamp and think about the huge difference. Less contact surface area means greater pressure will be needed for the same ability to hold the post.
This pinching internal binder has been done quite a few times over the bike industry's history. A well known version is the Fregus from the 1960s and 1970s. Try to find a replacement binder bolt set these days, oh and you better know which subtly different version your bike needs. Andy |
Looks like a Look to me. I have a Look 481sl that uses a binder bolt like that. The bike comes with a carbon seat post
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Originally Posted by alcjphil
(Post 22605153)
Looks like a Look to me. I have a Look 481sl that uses a binder bolt like that. The bike comes with a carbon seat post
I hope the carbon post has been designed with the pinching binder in mind. Carbon isn't best used when localized compressive forces are at play. Andy |
Originally Posted by Andrew R Stewart
(Post 22604799)
There are usually more than one reason why a design isn't used commonly. In this case the lesser ability to hold the post in place, compared to the usual slotted clamp design, is likely a big reason. Just look at the surface contact area of this design and look at a common slotted clamp and think about the huge difference. Less contact surface area means greater pressure will be needed for the same ability to hold the post.
This pinching internal binder has been done quite a few times over the bike industry's history. A well known version is the Fregus from the 1960s and 1970s. Try to find a replacement binder bolt set these days, oh and you better know which subtly different version your bike needs. Andy |
Originally Posted by alcjphil
(Post 22605153)
Looks like a Look to me. I have a Look 481sl that uses a binder bolt like that. The bike comes with a carbon seat post
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In the few searches I did I could not find a replacement and so I guess I better not lose this bolt.
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This binder doesn't look too hard to make. A motivated person with basic metal working skills and tools (Tap, drill, file, hack saw) could do it. A machine shop would likely do it nicer and want more than a few dollars. If you're near Rochester, NY drop me a PM. Andy
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Originally Posted by Andrew R Stewart
(Post 22605735)
This binder doesn't look too hard to make. A motivated person with basic metal working skills and tools (Tap, drill, file, hack saw) could do it. A machine shop would likely do it nicer and want more than a few dollars. If you're near Rochester, NY drop me a PM. Andy
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Please do who ever has to duplicate this binder and record the dimensions and take better photos for reference. Otherwise a fairly simple fab job turns into a bigger design and hope it works one. That bigger job will be best done with the frame in the hands of the fabber. Andy
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Originally Posted by Andrew R Stewart
(Post 22605302)
I hope the carbon post has been designed with the pinching binder in mind. Carbon isn't best used when localized compressive forces are at play. Andy
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Originally Posted by alcjphil
(Post 22606501)
The seat post that came with the frame is a Look product. I have owned 3 Look frames that used the same seat post and binder bolt arrangement. I assume that Look knows what they are doing
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