Contact surface area shouldn’t have anything to do with power transfer… that has much more to do with how much play your foot has in your shoe, how flexible the sole is, and whether there is play in the cleat-pedal interface.
I’m surprised that no-one mentioned the amount of float (free-side-to-side-movement) that the different pedals offer. I have a bad knee, and can’t run SPDs ever. They only have 7 degrees of float, and tend to feel like they lock-into a single position. I run egg-beaters on my commuter, and speedplays on my road bikes. (I have run time, look, shimano-both spd and spd-sl, frogs, and these are just the most comfortable for me.)
You can also check out bebops. The seem to be a pretty cool pedal system.
Insofar as shorts: the chamois is critical. Don’t spend less than $65MSRP, as the lower quality chamois usually break down quickly, and or they don’t have as many panels and thus don’t fit as well. Make sure also that the shorts have some sort of material to keep them in place at the thigh (most good shorts have a silicon band at the bottom to keep them from riding up on your leg.)
Good luck and god bless!
TCE (Thecyclingeconomist)
