Originally Posted by
CliffordK
The question is which came first. Before a multi-million settlement, one could try building a frame with the HT welded to the DT, but not welded to the TT. Then see if one can get the same DT bend. I'm not sure the above bend could happen without a significant crash with both welds intact.
I think you would still get those ripples. If you just weld one bike tube to another and try to break it off there's usually lots of bending before anything breaks. Actually a good test would be to take what's left of the bike and try to snap the top tube off the seat tube. If it snaps off easily and cleanly then there's a problem. It should bend around the butted area in the middle and basically be pretty much impossible to break.
The round tube is 0.8mm wall 4130 cromoly from an old Trek 520 (whose frame failed elsewhere). I've welded it onto some 1.6mm wall mild steel square tube using ER-70S2 filler wire.
Now to test it... To get it into this state I had to really whale on the cromoly chainstay with a 1kg hammer. As you can see it's deformed considerably, with plenty of ripples, and still nothing has actually broken. I think this is roughly what's supposed to happen. Not that it just snap right behind the weld.