Re: army bike
I've been reading about how great the NuVinci hubs are too - I should hopefully be able to find out first-hand in the next couple of days (that's when UPS says my parts should arrive). I bought the NuVinci hub from TreeFortBikes.com for about $150 less than anywhere else I could find - which was great, except that it didn't come with a freewheel/sprocket. So then I ordered that part from yet another website, and until just recently it has been backordered forever.
I decided on a 16-tooth freewheel, because I read another post in these forums from a guy using an 18-tooth sprocket on his NuVinci, and his description sounded like more low-end power, not as much high-end (if I'm remembering correctly I think he said his top speed was 30mph).
Another thought if you're thinking of a NuVinci hub - measure the distance between your rear drop-outs, because the NuVinci is roughly 140mm wide. I have a steel Micargi cruiser designed for a typical coasterbrake hub, and I had to spread the drop-outs apart using a length of all-thread and some nuts. This worked out really well on my steel frame, but I've heard that aluminum frames cannot be spread apart as easily.