Being in control of a vehicle with awesome power and making progress better than any other form of road user... The ability to (safely) pull off over-takes you wouldn't even consider on or in any other vehicle... the pure sensation of reading the road and leaning the bike round bends and striving to remain in perfect control, carving a smooth line from one to the next to the next. The fact that every ride is different with something new to learn or discover each time. And, as Jaydee said... because I can.