Using the BL36 kit on a 26" wheel, your bike will reach a top speed of 20 mph. On a 24" wheel - 18 mph, and 20" wheel = 16 mph. Using the BD36 kit on a 26' wheel, your bike will reach a top speed of 25 mph. On a 24" wheel - 22 mph, and 20" wheel = 20 mph. If you are thinking about purchasing a bike to install your Bike Electrified kit on, keep this in mind: different wheel sizes will give you different speed/torque performance. So, you should decide what is more important to you: top speed, or accelleration/hill climbing ability. If you're going to be climbing San Francisco type hills every day, then you should probably get a 20" bike. On the other hand, if you live in Kansas, a 26" or 700C would be better since you will cruise along at 22+ mph. Smaller wheels = torque, larger wheels = high top end speed.