Well I am looking at a 48v 450 watt system now and maybe the SHORAI Lithium-Iron Powersports battery, 18Ah 12V ( 8 of them). This battery pack will give me 37AHr at 48v. The pack will weight 17 lbs. That way if a cell goes bad then just pull the battery and replace. My bike is 22lbs, and I'm 170lbs. As we all know a 48 volt system can reach speeds of 60mph. But the amps is what makes it get to speed fast. And yes wind or air drag is a big problem. I'm still working on that LOL. Man my head hurts