What diameter/thickness tubing for curved seat stays?

[joth jacobson]

This is basically a follow-up to my post last week on how to bend in 2 dimensions. I think I have a process that will work, thanks.

I've rolled some 5/8" (16mm) x .035 4130 straight guage to use as curved (cruiser-style) mtb seat stays. I notice with the long rolled piece (6'), that it's fairly flexy along the curved axis.

Will this be sufficient for mtb seat stays? Would 3/4" x .035 be better? Or does cutting down the long piece into a useable length create adequate rigidity?

It's hard to tell from pictures what others are using, seems to be a mix of 16mm and 19mm, and of course tapered tubes.

I've used 16mm x .035 rolled as curved stays on a previous bike that's still kicking along after 2-3 years. My concern is more with the long-term durability of the chainstays from flexy seat stays.

I acknowledge that this is a very subjective question. But wanted to get opinions/experiences from a group that's been around the block with this issue. Thanks.

[Jake Rosenfeld]

.625x.035 is Perfect . .028 would probably be fine too but it doesn't bend with as much success as .035.
As far as being flexy, cut it down to size,weld it into a triangle shape and see if you still feel the same way....