Originally Posted by
unterhausen
Even a longitudinal crack in a chainstay is going to see forces that will probably break brazing.
Could be, could be. My gut feeling that it will last forever is informed by 20+ years of custom frame building, but it's still just a gut feeling.
In favor of it lasting: the bottom of the indent is closer to the neutral axis for twisting loads, and closer to the neutral plane for sideways bending loads (chainstays see both). Stress flows to the parts of the stay farther from the neutral. I bet in one of those false-color representations of FEA analysis, the bottom of the crease will be blue or whatever color indicates low stress. That's why I like a relatively sharp (small radius) crease at the bottom of the indent -- stress avoids that area. Again, gut feeling (grain of salt recommended!), but frames made with that sharp crease have been around for a long time and don't break there.