[morganw]

That's really helpful. It predicts 534 Watts to get me (110kg, 0.4 CdA) to the 45kph limit for Class 3 California bikes.

The Grin Technologies motor simulator https://ebikes.ca/tools/simulator.html predicts (the "Load Line") 837 Watts for "MTB upright", 648W for "MTB, Tuck" and 570W for "Road, Tuck".

I do find that in an upright position it takes 100-200W of human power in addition to 750W power measured at the input to the motor controller. The controller's pretty efficient, but the motor (GMAC) is only 85% max, so there's maybe 570W at the axle. The US CPSC and California laws aren't clear whether the 750W/1 horsepower limit is power in or power out, but power in is what shows on the display, so I limit it to that. Also, even a mild grade will cause the motor to approach the 70 deg C limit I chose after 1 minute. I live in the flattish Santa Clara County, but I'd definitely want a mid-drive if I lived in a hilly area. A 250 or 350W Riese & Müller Delite https://www.r-m.de/en-us/bikes/delite/ I test rode needed a lot of human power to hit the 45 kph max, but it climbed hills in Larkspur like a goat.

750W will have no problem getting a recumbent bike to 30MPH, but don't count on it for an upright.