More info about the bike would be helpful but probably a Bafang mid drive kit with a quality battery.
Bafang or Photon mid drive or rear hub drive probably, but don't forget you need a controller, and you really don't want to get a sketchy battery.
A mid drive would let you take advantage of the bike's gears while a hub drive would reduce wear-and-tear on the bike's regular drivetrain, but it won't be able to use the gears at all.
Secondinging this
Ebikes, bicycles, scooters, skateboards, longboards, eboards, motorcycles, skates, unicycles, heelies, or an office chair: Whatever floats your goat, this is all things micromobility!
"Transportation using lightweight vehicles such as bicycles or scooters, especially electric ones that may be borrowed as part of a self-service rental program in which people rent vehicles for short-term use within a town or city.
micromobility is seen as a potential solution to moving people more efficiently around cities"
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