i have two fixes, one with a frame that's too big and one that's too small. sometimes the top tube of the big frame rubs up against my thigh when i'm trackstanding (standing up, two handed) and i occasionally use it as another balnce point. never hits very hard though.

i find bruises on my quads, calves, around the knees, etc take longer to heal. i assume it's because i'm working those muscles more, but i don't really know.