as i recall, columbus slx seat tubes were an immediate reaction to the braze-on front changer mounts which had previously been in the marketplace. too many problems occured. procuction-type frames with 'unsupported' seat tube sections were braking as a result of adding the braze-on tab. yes, silver could be used. most used brass, though. and, as all braze-on pieces were in those days, the tab was added after the frames were built. WRONG!!!!!!!!!!!!!!!!!!!!! the only way to add these bulbous, assymetrically placed bad boys was, and is, to braze them on to the seat tube BEFORE the seat tube is part of the frame. ribbed tubing, once available, reduced possible failures. but any time the brazing sequence allows that the piece in question is added afterwards, ribbed tubes or not, it is a recipe for a possible future 'issue'. e-RICHIE
On Mon, 26 Mar 2001 08:30:56 -0800 "Diane Feldman" <feldmanbike@home.com> writes: Also, two product development rumors--that Columbus developed ribbed tubing to reinforce the brazed area (can't quite believe this; a ft. derail bracket could be silver brazed at very low temperature) ...