Good choice on the nine continent. That's a pretty efficient motor. For the batteries, I'd go with a 36v40 AH Thundersky or Sky Energy from evcomponents.com.

You could get 30 x 2 = 60 miles out of the pack easily without pedaling. If you pedal, you could easily get 80 miles out of it without the pack even breaking a sweat.

They are kind of expensive but these are the cheapest and best lifepo4 for your money on the internet. I recently bought the same kind but I got a 36v20AH thundersky.

$44 for a 3.2v 40AH cell
http://www.evcomponents.com/ProductD...=TS%2DLFP40AHA

Get 12 cells for 36v. That'd be about 12 x 44 = $530 + shipping and extra = $600. The same pack at other places would cost you probably $1000.

It's up to you. I recently upgraded to lifepo4 and it's amazing. The difference is huge. You'll be spending probably $150 - $200 for the SLA's anyway. Remember that once you are done riding with the SLA's, you have to let them cool and then charge them immediately. You don't have to do that with lithium. The lifepo4 will last you 5 years or more or 2000 charges. The SLA's might last a year.

If you do get lifepo4, make sure you learn how to properly use them.