• Anyone ever bonded a shim into a seattube?

    I'm repairing a crash damaged Orange P7 which has a 29.8mm seattube and (I think) came with a shim to take it down to 27.2mm to allow a wider range of posts to fit.

    I think the seattubes are heavy enough to be used without the shim (a colleague has one that he uses with a 29.8mm Thomson post) but given that I need to braze a new toptube and chainstay wishbone to it I suspect the seattube may end up a little bit off round so retaining the shim would seem to be a good idea.

    However, I will want to run a qr seatclamp to lift and lower the seat to suit the terrain and I don't want the shim coming out with the post (I can work a qr clamp and lift the post with my thighs without getting off the bike) so I'm thinking I should maybe glue the shim in but I don't know what glue to use.

    Gorilla glue expands as it cures so that's clearly no use, I don't know what other glues expand as they cure. Something that wasn't a ridiculously strong bond might be a good idea too, just incase I should ever want to remove it down the line.

    The frame came to me with a shimmed and well worn 27.2 post that slid in and out alright while leaving the shim in the frame but I removed the shim before starting the repairs and I think the reason it was staying in the frame was that there was a bit of rust holding it in place. I'd like something a bit more reliable/predictable than rust!

  • I have:

    I cut it down flush with the lug afterwards of course. I used JB Weld, but if you might want to remove it in the future JB Weld might be a bit excessive. I've used it in the past for repairing an engine block, and it really doesn't give up without a fight. Brompton seat post shims are held in place by rubberised superglue like Gorilla Superglue so you could try that.


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