after heavy braking, the pads get hot and dont work as well, if they get hot enough, the brake fluid can boil/turn to steam.. it happened to me once.. had a good solid lever(on a chopper,front lever activated rear caliper) but had no brakes.going down a big hill, i rolled through a red light at the bottom, and 4 lanes of traffic dragging my feet before i stopped.. i parked and looked at it, found nothing wrong. brakes worked like new after a few min of cooling off

 

Not trying to hyjack the thread, but I had my FXDC at the dealer for a dyno tune recently & they gave me a Fat Bob as a loaner for the day....man, the dual front disk brakes make a HUGE difference. I wonder why they don't put dual disks on all bikes? It stopped so much better than anything with the single disk.