FWIW, I have a street bike that when run on the right voltage battery has similar power to Markz. Most of the time, I prefer to run 48v, and limit wattage to around 1500w.
90% of the time I ride it slow, at least relative to its top speed of 32 mph. I like to ride 18mph, because with the bikes gearing, top gear is my comfortable pedaling cadence at 18 mph. This pedaling helps my range, but mostly by riding slow, not my puny effort.
The result is about the same as if I rode 30mph, that bike stays in top gear 99.9% of the time. I only shift down to limp home with a 98% used up battery. Its a 7 gear bike, and it stays in 58 front 14 back all the time.
My off road bikes are different, they do shift a lot, and mostly ride in gears as low as 38 front, and middle of the cluster in the rear. But even so, 7 rear gears is plenty. With the motor, you don't need a cluster with lots of choices.
One off road bike is 1000w, and it gets pedaled continously in a middle gear. I ride it about 12-15 mph. The other bike is 2000w, and gets pedaled only when its stalling out in bottomless sand, or hills of above 20% grade. I ride it like a trials motorcycle most of the time, standing on the pedals. I leave it in that middle gear, rarely shifting, and pedal only when I slow to 10 mph by a hill or sand. It goes 25 mph most of the time. ( slow wind motor, or it would be 35 mph)