A great project for somebody who wants to get started in electric vehicles. Electric bikes are great for short commutes and general errand running. I have to admit that I've been looking forward to this project for a long time and am glad that it's here.

First, the question of why build an electric bike? Well, you can get an electric bike now for $400 or so, but what they don't tell you is that you'll have to replace the batteries every year. The lead acid batteries used in these cheap bikes aren't designed to be deep discharged and that's why they only last for a year. On the other hand, an electric bike with a good motor and good batteries costs $3000... which is much to expensive for my budget. Let's take a look at the research I've done (building an electric bike will soon be in our tutorials so stay tuned).

To start out with we're going to need a motor. One of my main goals with this project is to keep the bike looking like a normal bike (less chance of it being stolen). I'll be accomplishing this in several different ways and the first way will be the motor. A genius guy figured out how to make the hub of a bicycle wheel into a motor. These "hub motors" are great... it doesn't really look like a motor and they are quite efficient. Hub motors are available for both the front and rear wheels, but I'll be going with the front wheel hub motor to save on the cost. Each of these motors cost about $300. That gets the most important part out of the way. Let's take a look at batteries.

The goal here is to have batteries that are very safe, last a long time, and have a high capacity. Lead acids are out of the mix because they're heavy and not as efficient as some newer formulations. There are new batteries on the market called lithium polymer which have superb capacity; however they only have 300 charge cycles and they are very sensitive to how you charge them. Than I stumbled up Lithium Iron-Phosphate batteries. They have a similar capacity to Lithium Polymer, but they can do 2000+ charge cycles, and are very tolerant to different types of charging. Each battery holds about 3.5 volts (we'll be operating at 36 volts). That means we're going to need about 12 of them. They're each $17 (we need 12) so total cost is $204. Don't let the high cost deter you. The motor and batteries will probably outlast your bike. These batteries are cylindrical and I've figured out a way to mount them so it doesn't even look like they're a part of the bike (that will be in the tutorial).

Now it's time for some miscellaneous parts. We're going to need a charge controller and a bike controller. I'll be using the same micro-controller from the charge controller for this. They're really cheap and we can hook all the sensors up (regenerative braking, etc). The total cost (plus other components) will probably be in the $100 range.

So we've covered the motor, batteries, and all the misc. parts and the total cost will be around $600. Let me emphasize that this bike will be better than the $3000 bikes. It will go 25 - 30MPH (you don't want to go faster for safety reasons) and will have a range of around 30 miles.

I've just laid out the basic principles I'm going to use for the bike. If you're interested keep checking back here and also check for 'Building Electric Bike' to appear in the tutorials menu at the right.

If you have any questions feel free to leave a comment and I'll do my best to answer them.