E-bike kit purchase - questions from a newbie

[Big Tom]

I just saw this, brand new to the market It says you can use a cassette. It appears to be a monster motor.
https://lunacycle.com/double-gear-double-torque-motor/

 

[harryS]

Big Tom, that's a xiongda double geared motor. The internal motor actually stops and spins backwards to engage a lower set of gears. It's not intended for speed, and 25 mph is well beyond its capability, It was intended to allow a small motor to pull a heavier load, .i.e, climb steep hills.

I was going to get one for fun, but I don't think it would have been much fun. Early versions could not be rolled backwatd w/o stripping the gears.