"Trials riding is an extreme test of bicycle handling skills, over all kinds of obstacles, both natural and man-made. It now has a strong – though small – following worldwide, though it is still primarily a European sport. Skills taken from trials riding can be used practically on any bicycle for balance, for example controlled braking and track standing, or balancing on the bike without putting a foot down. Competition trial bikes are characterized by powerful brakes, wide handlebars, lightweight parts, single-speed low gearing, low tire pressures with a thick rear tire, distinctive frame geometry, and usually no seat."
Now, if all of that adds up to "a sport in which insane people use bikes to traverse mountain paths where most wouldn't dare set foot" then it's right on target. This video shows MacAskill using his bike to make amazing moves and jumps as he weaves in and out on a winding trail at death-defying heights. This man has as much courage (or crazy) as he has athletic prowess.