If I were to build a bicycle hub motor, it would be BLDC, with a controller from Luminary.

A tubular pack of a LiFePo4 battery 12v, 40 amp hour battery is here. It is inexpensive to build, as it uses the 38120 batteries, threaded studs to connect the batteries, and buss bar to join the individual series combinations, and 100 amp fuses, and shrink wrap. Both backs require a BMS.

A prismatic pack of a LiFePo4 battery 12v, 40 amp hour battery is here. It uses the same batteries. The 3-D model is a viewable, rotatable, and zoomable picture. Here is the specification on the batteries. This might be a cantidate for an EV pack, bicycle or car. Each module costs $290 for batteries only. It is more expensive as it uses lots of buss bar and machined G-10 covers, and bent Plexiglas, in addition to the threaded studs.

The BMS , used on both battery packs is one that has been developed for low $, that balances a pack, and provides a signal if one cell voltage goes below 2.1 volt.