It may vary due to a variety of factors including a person's size, topology, power demands of the motor and controller, whether the rider is pedaling and battery storage capacity (the more AHs the better). I added a Currie, non-hub motor conversion kit to my 21-speed mountain bike last summer. It comes with 1 24V 10AH SLA battery and I easily biked over 25 miles, with pedaling and still had power in the battery pack (I got power assist to help my old runner's knees tackle the steep hills here in the mountains of the far northern US Rockies, I like pedaling and don't really ride without pedaling). This spring I built my first LIFEPO4 pack, a 24V 20AH pack. What a difference that extra 10AHs makes. I haven't taken this new battery pack down to the deepest depth of discharge that's safe yet. I calculate that with the new LIFEPO4 pack and my original SLA, which is still working but starting to loose capacity, I can easily travel around 40 miles or more (yes, with pedaling, but I like to pedal). I plan on building a second LIFEPO4 pack and it will be 20AH again.