[JesseK]

Excellent concept. Though I worry about the end loss of the final gearing stages. Usually gears are averaged to a 97.5% efficiency per gearmesh reduction, yet you have 12 possible gearmeshes at once. Even at a very generous 98% efficiency per reduction (which must include bearing losses as well) it's still 0.98^12, which is only a 78% efficiency regardless of what gear it's in (since all of the primary and secondary gears are always connected).

This isn't to say that this isn't a fabulous design -- it simply says that there is a point where it will become highly impractical to keep adding stages to the transmission. Due to traction, current draw under load at max speed, and other issues, I'd expand the gearing in between stages and go for (max!) 4 stages that vary from 3-4fps to 13-15fps.

Regards