The present invention provides an auxiliary power system to provide supplemental power by compressed hydrogen. The invention also provides a method for obtaining said in vivo imaging agents, and use of the in vivo imaging agents in determining \u03b1v\u03b26 expressed in a subject. An inboard end of each crank arm is rotatably mounted to the bicycle at a bottom bracket of the bicycle. The selective live tool drive train includes an axially movable drive shaft and bevel drive gear for selectively engaging the driven bevel gear of the desired live tool.