a sport requires physical activity, rules and competition, so no, i don't think motorcycling is a "sport". for most people, it's a hobby, for some, a very reckless one. if i go for a run, it's not a sport, it's a hobby or exercise. if i'm trying to run faster than a bunch of other people on a set path, it's a sport.
by any definition other than an "active pastime" or "recreation" riding a motorcycle on the street SHOULDN'T be a sport. outside of a track no rules are followed, they are only broken, and there should never be any competition. i think this idea that motorcycling is a sport and can only be enjoyed at high speed is what is getting people killed every weekend.
i'm sorry folks, but get over yourselves. unless you're in the afm or something similar, you're just a guy with an expensive hobby. riding motorcycles, on its own, is not a sport. rules, physical activity, and competition; otherwise it's just a hobby.