[Jared Russell]

I will sum up my experiences with live and dead axles below.

Live axles are useful because:

• You can drive them from any point on the shaft (e.g. West Coast Drive where there is a bearing block between the driving sprocket and the wheel).
• The keyed/hex shaft becomes a "universal" interface for attaching wheels, bearings, sprockets, gears, brakes, encoders, etc. As long as your piece has an (ex.) 1/2" keyed bore, it will rotate along with everything else on the shaft. With a dead axle, you must attach pieces to each other directly, and not all wheel and sprocket combinations play nice in this regard.

Dead axles are useful because:

• You are minimizing the rotational mass of the wheel assembly and therefore maximizing efficiency since the shaft itself doesn't need to spin. Unless you have a truly massive axle or bad bearings/alignment, however, we're probably not talking a huge difference.
• In the cantilevered case, you are minimizing torsional loads on ball bearings with dead axles (since the bearings are still centered on the axis of rotation no matter what the deflection of the shaft).
• The closer together two bearings are, the easier it is to have them stay aligned. In a dead axle setup with two bearings in a single wheel, alignment is trivial. Live axle systems that support both ends of the shaft can get out of alignment more easily.

Did I miss anything?