The e-RAD BBS HD-1000 Mid Drive Electric Bike Conversion Kit is one of the most powerful electric bike motors available, ideal for heavy duty cargo hauling, blurs the line on legality shipping with 20 mph top speed limit but unlockable to ~40 mph for off-road use. Offers physical shift detection compatible with cassettes, internally geared hubs and CVT systems like NuVinci, this reduces drivetrain wear on the chain, sprockets and derailleur significantly. Three battery size options (all run at 48 volts) with premium Samsung, Panasonic or Sanyo Lithium-ion cells, solid one year comprehensive warranty on all parts. Choose from trigger throttle or twist throttle (for left or right bar), you can wire in lights, the system lets you override pedal assist with the throttle and the display looks great but doesn't swivel and isn't removable, as with most aftermarket kits the wires use zip ties to attach and may add clutter to the frame
It would be legal in Utah at 1000 watts, if you left it with the stock 20 mph limit. That's on the street. I'm surprised Bafang is not working harder on sophisticated shift sensors as part of the motor. In Turbo Bob's quick HD video, the shifts were pretty rough. Just compared to the European systems, Bafang is coming up a little short on refinements, as they up the power.
It's getting to be way too expensive if you don't need the power. If you did want all the power, I'd work very hard on the design of the bike to make sure it could handle it, and that the ride wouldn't put you on the list for a new kidney.