It seems like every 3rd or 4th ride I go out on, I end up coming back with 1-3 broken spokes. It happens in either the front or back wheel, so it's not just one of them. I like to keep both wheels "on the ground," so to speak, so it's not like I'm flying through the air and landing hard. I do ride down hills, through rough, rocky, rooty terrain with marginal drop-offs (8" high at most) at a pretty fast speed, though.... The wheels are Sun rims CR18, that came stock on the bike (Specialized Rockhopper).