I bit it about a decade ago coming down a mountain. I was bombing as I was going in to a turn and a car started driving up at the same time. I panicked and jammed on the brakes as I was turning. The bike slid out from under me and I ended up with a lot of soft tissue damage. Too me years to get comfortable on the bike again. I climb hills quite well and pass quite a few folks. But I no longer bomb down them and those who I passed on the way up, pass me on the way down. And I'm ok with that.