Is it riding into a head-wind on the last stretch of your ride?
That's mine. I hear Danny Glover from ~~Die Hard~~ Lethal Weapon in my head every time...
EDIT: Correct movie referenced
Noisy brake rotors.
Mud, deep puddles, creek crossings, thick brush, snow.. none of that is an issue for my bike, I can just plow right thru it all. However that means the next 10 minutes is spend pedaling against the brakes trying to heat them up to the point they start gripping again and stop making that awful sound. I'm pretty much at the point that I'm starting to desing enclosures for my rotors to protect them from water and mud.
