It should also be noted that the technology for downhill mountain biking has exploded in quality and price -- probably also money from manufacturers sponsoring

It should also be noted that the technology for downhill mountain biking has exploded in quality and price -- probably also money from manufacturers sponsoring pros etc. Making it viable for super sketchy terrain (via tires, suspension, frame dynamics, braking) to be taken on and cliff drops to be attempted. Its probably the quickest advancing "extreme" sport happening right now - which would track with this finding since they are pushing the boundaries and the landings are HARD. For example go see the highlights of red bull rampage for the current mtn biking zeitgeist.