The drivetrain requires special attention. There's no sense in spending hundreds, if not thousands, of dollars to save a percentage or two on battery efficiency if you're going to waste it all as heat going through the transmission.

There are three basic ways to transmit mechanical power along the drivetrain to the wheels: chains, belts, and shafts. My initial focus was particularly on chains, as my motorcycle already uses a chain. In any case, the only other possibility would be belts-- from what I understand, shafts are to be avoided on motorcycles as they're heavy and not as efficient. On cars, they're probably the only way to go.

For an good breakdown of chains vs. belts vs. shafts, click here. However, note that in real world terms the comparison is probably incorrect when it comes to efficiency. Chains are far more likely than belts to suffer efficiency losses due to wear, dirt, and grime.

Read my explanation of chain design and selection.