Hey Twist

[Biker Dude]

0

My mountain bike seat post will slip, slowly, but it slips no matter how tight I get it. Other bikes have no problem. If you come up with a solution besides welding it let me know.

If it is using a pinch clamp something like this

You can go in between with a file and take some of the material off. That would allow it to pinch tighter.

You could also tack weld on the seat tube, that would stop it from going in farther, but wouldn't be 'welded in'.