My M625 system (has no leads for shift sensor) , I have 'Y' splitter so shift sensor is in the same lead as the rear brake (motor cutoff). But this doesn't seem to work ie. up shifts to a higher gear is usually a noisey clang. If I simulate the upshift by lightly applying front brake to cut motor, the shift is smooth. Any ideas? Is the shift sensor motor cutoff too quick for my bike? I read that it is only milliseconds.