On Jan 24, 7:21 pm, Michael Press wrote:
At a later point in the brake
application, the braking force suddenly increased
sharply. This happened more than once. Had not seen
this before, and need more experiments. Any comments on
this sketchy account?

I had something similar happen when I was using different sets of
wheels with rims that didn't match in the rim brake path (Nisi Mixer
with triangular profile, switching to box-section tubies to race on).
Brake pads worn on the Mixers contacted "boxer: rims unevenly. Going
for more stopping power, more shoe area would contact the rims as the
brakes were pulled tighter, so I got more squeeze plus more brake pad.
One emergency slow-down to avoid a crashing rider sent me over the bars
when the front brake worked all too well, all of a sudden. It hadn't
been a problem (the usual multi-turn crit race) until I tried to use it
real hard. (You've probably checked pad-to-rim "engagement" already,
posting "JIC") --D-y