Motorcycles aren't called "donorcycles" for nothing. The risk level seems to be intrinsically high, though it seems to be held up by bikers not wearing helmets:
The documented risk of dying from a serious head wound while riding without a helmet is so high, bare-headed motorcyclists are considered ideal organ donors: They're typically young, otherwise healthy and at high risk of brain death from sudden trauma.
http://articles.sun-sentinel.com/2012-06-10/health/fl-motorc...
The documented risk of dying from a serious head wound while riding without a helmet is so high, bare-headed motorcyclists are considered ideal organ donors: They're typically young, otherwise healthy and at high risk of brain death from sudden trauma.