Originally Posted by
guy153
Yes this style has plenty of surface area and should be very strong. The ones Brodie did (that I was surprised by) were just mitred straight in (I think it's called the "shot-in" style?). So that you only really have contact along the cross-section of the tube (although it is cut at a fairly steep angle).
'Shot-in' is common British usage I believe, with 'fastback' more common in the US. Dunno how that got started, but it's well established.
It's a pretty reliable method, failures are rare, although we had a thread here last year about some brand that was breaking there, Kona maybe? Pretty sure it was the seat tube that cracked, not the weld.
If the seat tube isn't reinforced with a lug there, it had better be a fairly thick tube, for example the externally-butted seat tubes made extra thick at the top for just that reason. But you almost never see the braze (or weld) break, it's almost always the seat tube. That said, if you use high silver-content filler, your miters had better be perfect.