I’m interested in converting my standard bike to an E bike using a rear hub drive motor...My rear hub spacing is 148mm. I know there are several rear hub motors available, I know maxon makes one. Any others I should be looking at? But mostly I’m looking for a battery that small and discreet. I wouldn’t use the power that often just go up a hill so I don’t need a huge battery life. Again, I know there are various systems available, but i’m mainly looking for something that doesn’t make my bike look like an ebike.