Here are the speed for different motors:

　

4011 Motor   "  ON-ROAD use  "  Very High Torque Motor 

Condition: Motor start in 0km/h / 26" wheel size / Rider weight 75kg

24V 20km/h  

36V 22km/h  

48V 25km/h  

406 Motor         " For OFF-ROAD use only " Very High Speed Motor BUT Low Torque
Condition: Motor start after reach speed 5-9km/h / 26" wheel size / Rider weight 75kg
24V 32km/h  
36V 45km/h  

48V 55km/h  

 

408 Motor      " For OFF-ROAD use only " Speed and Torque GOOD for MTB 
Condition: Motor start after reach speed 5-9km/h / 26" wheel size / Rider weight 75kg
25.4V 27.6km/h
38V 40km/h   
48V 48km/h