Having replaced both screws back in March, I wasn’t expecting this:
Of course, it broke at the first pedal stroke while pushing off across an intersection, which is why I never try to ace out oncoming cars.
This was, mercifully, on the left side of the bike, so I could replace it without removing the rear wheel. Being that sort of bear, I now carry spare screws and we were back on the road in about ten minutes.
A closer look at the head end of the screw shows some interesting details:
The tail end has matching cracks:
Notice how the cracks are all oriented in the same direction. The screw fractured at the edge of the brazed-on frame fitting, so I suspect the seat stay clamp must be moving just enough to flex the screw across that plane.
I mooched a pair of hardened socket head cap screws from Eks, ground down the head of the right-side screw for better chain clearance around the sprockets, buttered ’em up with Never-Seez, and we’ll see how long Real Steel lasts.
I really should conjure up a clamp that mounts to the frame tubing, rather than depend on that puny brazed-on fitting, shouldn’t I?