Pack	4x Makita Lithium Ion Power Tool Batteries
Capacity	216 Watt-Hours
Configuration	4 series 1 parallel = 72 Volts 3 Amp-Hours
Max Power	10C => 30 amps@72v = 2160 Watts
Charge Time	1.3 Hours
Motor	Suzhou Bafang Geared Hub motor 1HP Rated (1500 watts/2 HP actual)
Gearing	5:1 internal planetary gears
Controller	Shenzen Sucteam 1500 Watts/2 HP

• Most electric bicycles are far too heavy
• Their motors are geared for a top speed of 15mph, which is slower than pedaling
• They are also bulky and hard to mix with other forms of transport, such as cars
• Most bicycles are not built with commuting in mind, lacking required features like lights

• Use aluminum frame, lightweight lithium batteries and geared hub motor
• Choose gearing and battery voltage to achieve at least 20mph
• Use a compact folding bicycle as the base bicycle
• Outfit with all necessary accessories– lights, fenders, rack, mirror, cycle computer

Use aluminum frame, lightweight lithium batteries and geared hub motor

A quick and dirty test at the Maker Faire in 2009 confirmed it: 40lbs is some sort of magic threshold for bicycle weight. Above 40lbs, a bicycle gets too heavy for most people to comfortable carry. A light motor and battery add roughly 14lbs of weight, so the math is simple. You can’t start with a 35lbs steel bicycle. The bicycle weighs 27lbs before the electric components are added.

Choose gearing and battery voltage to achieve 20mph

The 24 volt and 36 volt battery packs used by most electric bicycles only propel the bicycle at about 15mph. Since most riders can pedal up to 20mph (and 25mph for short periods), a standard electric bicycle ends up being slower than just pedaling by human power. While 48volts should achieve 20mph, the decision was made to go straight to 72v and see what happens. The result? 30mph top speed. Not bad.

Use a compact folding bicycle as the base bicycle

While 26″ bikes might be the norm, a 20″ wheeled folding bicycle is far more compact (really handy when you have a garage full of electric bikes!). The donor bike easily folds into the trunk of a car, the luggage rack on the train, or under a desk at the office.

Outfit with all necessary accessories

In lots of places, it’s simply not legal to ride without lights. The lights chosen (Blackburn Quadrant and Mars) not only make the bike legal at night, but with 4 bright LEDs each they are amazingly effective for their small size and weight. A bar end mirror makes lane changes much safer. The rear rack can hold saddle bags and also holds the batteries. The fenders are absolutely necessary for riding on wet roads, keeping the rider clean and dry. The cycle computer, while not necessary, is a lot of fun– it includes an odometer, trip meter, and speedometer and can be illuminated at night.