Thursday, February 20, 2014

 Lots of stuff piling up while waiting on powder orders and some low humidity days.

A new dropout for the little bikes

A friend brought this (random BMX) frame to the park and let me have it to cut up. I thought it weird that a frame that supposedly had Supertherm main tubes would break in such an odd place - the DT gusset had just about cracked off completely. When I cut the DT near the BB it was apparent that the miters might have been pretty sloppy. The DT shifted about 20mm when I got all the way through it. This was tension was probably a big contributor to the break. The bigger factor was an inferior welding procedure: the gusset was welded to the downtube and then mitered/welded to the headtube. Notice in the pic below that the crack propagated where the weldor neglected to weld the DT to the headtube first. They would have been better off not using gussets at all.

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