Parts for the EBR are beginning to arrive. Today I received the motor and controller. This is an AC-powered motor, originally designed for golf carts, optimized for electric vehicles. It features a peak of around 46 horsepower and almost 100 ft/lbs of torque, available at a standing start. This bad boy is rated for 7500 rpms which, coupled with a 96 volt pack and a 4.5:1 gear ratio, will push the top speed well above 100 mph.
I have a lot of other parts to procure, but having the motor and controller makes me feel like this project is on its way to completion.
Hey Dale, Fantastic project. Is the motor already geared in the picture? How are you planning to drive the rear wheel? Any other gearing or just a sprocket on the drive shaft? Very very cool! I want one too.
Hey Dave! No, I will need to put a sprocket on it and replace the one in the rear, too. It’ll use the same 530 size O-ring chain. I’ll have a couple different front sprockets so I can play with the gear ratio, but it’ll end up around 4.5:1. With a 7500 rpm motor, it should top out at around 125 mph, but the sweet spot will be in the 60 to 70 mph range. I can totally see you building one of these.
Why do electric bikes not use transmissions?
Hi John, glad you could stop by. Most bikes do not use transmissions simply because the electric motor has a sufficient RPM range to give you any street legal speed you need with a single gear ratio. Most e-bike builder build something in the 1:4 or 1:5 ratio range, e.g. a 12-tooth sprocket on the motor and a 60-tooth sprocket on the rear wheel. In the calculations for my bike, with a 7500 rpm rev limit, that was something like a theoretical 125 mph. If I change the front to a 15 tooth, it drops to a 1:4 ratio with a top end speed of about 105, but much better off-the-line performance.