So it seems like the best possible ebike motor would be one that has the benefits of the chain drive (using the bike gears) and also has the benefits of a hub motor (quiet, resistant to the elements, easy to install, etc).

How about a hub motor that is mounted on a rear hub that has internal gears? Would something like this be possible?

I'm sure there must be an obvious reason why this isn't already the most popular the most popular conversion to make an ebike, and I just don't know enough about it yet to see it.

Does anyone sell a rear wheel brushless hub motor conversion kit that has an internal geared hub?

http://en.wikipedia.org/wiki/Hub_gear

I would think a hub motor could be put on one of those just the same as any other hub, right?