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I have a Jamis TAXI beach cruiser needing repair. Part of the bracket that is welded for holding the seat post clamp in place has come loose. The frame says T6 6061 aluminum.

I am having trouble finding anyone to weld the piece back on. Can it be repaired without welding? How about grinding the other half of the clamp off and using a new clamp that goes around the tube (OD 31mm+)? How about putting a bolt through the tube for a fixed position (would this weaken the tube)?

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Pictures: https://photos.app.goo.gl/2FWGkogtMTbUZkU98

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    Use a new collar, cut then grind off the excess, careful not to over heat the tube. Do not weld, do not drill and use a bolt.
    – mattnz
    May 17 at 0:33
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    @mattnz that's an answer, and I agree with your suggested plan.
    – Criggie
    May 17 at 4:24
  • What worries me more is that bit that has left this gap in the seat-tube where the eyelet has broken away. I'd try to fill it up with some epoxy or similar to take the pressure of the collar.
    – Carel
    May 17 at 19:25
  • @Carel Which gap? Do you mean the slot? The seat tube can’t grip the seatpost without there being a slot...
    – MaplePanda
    May 18 at 15:44
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    @MaplePanda : the hollow-out left of the slot where the eyelet for the bolt has broken off.
    – Carel
    May 19 at 6:28
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It is aluminium, it is a material that do not like welding, even less drilling through it.

In my opinion, you are left with one reasonable option only, as mentioned by @mattnz, remove the other half of the bolt clamp and then use a new clamp.

Please use the longest seat post you can find, to avoid stressing the top part of the seat tube. Given the failure you had and the laid back posture on a cruiser bike, it may be helpful to place the new clamp with the bolt in the front, not on the back.

You have also a crazy option : banana seat, as explained in this video from Youtube.com

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