When I first got my hardtail I installed some clipless pedals. I was new to mountain biking and new to clipless pedals. I then proceeded to read how to descend steep inclines and decided to test it on a set of stone steps close to my home. I was rolling down too slowly (chicken-**** factor) and couldn't unclip in time as I slowly toppled over and really twisted my ankle and my knee. My ankle was inflated like a softball but a good regimen of ice-water/warm-water brought down the swelling fairly quickly but my ankle hurt for the longest time.