There are numerous e-bike drive systems available, each using either a mid-drive pedal-assist or a wheel (hub) assist motor. Mid-drive systems like those from Bosch or Shimano provide power through the cranks and pedals of the bike and enhance your pedal stroke -- so you must be pedaling to engage the assist.
Mid-drive systems now make up approximately 90% of the e-bike market, and Bosch is a worldwide leader in the category. Their mid-drive system is light weight, centrally located on the bike, and the direct power is extremely efficient. With 4 different drive units, and various battery options, Bosch makes systems for electric bikes designed for recreational riding, commuting, off road riding and even cargo bikes.
DRIVE UNITS, POWER PACKS & ON-BOARD COMPUTERS OVERVIEW
Similar to Bosch, Shimano offers a mid-drive system for e-bike manufacturers. Shimano's systems are lightweight and smooth riding. With the drive unit placed around the crank, the bicycle's center of gravity is kept low. The 3 tiered controller system gives you the option to run low, medium or high assist levels, or run the bike without assist.