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Good & easy way to add a seatpost clamp to a frame without one?? (quill style post)

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Good & easy way to add a seatpost clamp to a frame without one?? (quill style post)

Old 05-07-21, 10:03 AM
Lars of NM
Join Date: May 2021
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Adding a binder bolt

I have a 1985? Puegeot Triathlon made with Vitus 980 that uses a quill seat post. I am considering the above modification. The front mounted clamp that Nate does is not new I saw it on a bikes in the late 70's a except there was no horizontal slots just a vertical slot with stress releif holes top and bottom. There isn't alot of clamping movement in the mid tube clamp design. The seatpost has to fit correctly (snug) for this to work. to reduce the tube diameter by 0.1mm you need to reduce the cicumfrence by PI . So you will see 0.31 mm of slot narrowing for each 0.1mm of seat tube diameter reduction.
My bike also came with a 26.4 seat post that is a sloppy fit. I measured the seat tube ID at 26.9mm with a cheap caliper. I thnk the correct size seatpost is 26.6 or 26.8mm. It is not 26.4. i will need to do test fits amd determine the best fit before i start. The top of my seat tube and lug was oval because of the original undersized seat post. I rounded the seat tube/lug by gently expanding the quill at the top of the seat tube which seemed to work well.
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