My mountain bike has been sitting in the garage for more than two years. It hasn’t been ridden and it was in dire need of maintenance and repair. Its a big heavy bike that is exhausting to pedal around a hilly city. It was just taking up space.

With my recent change of jobs I significantly extended the distance of my commute. The routing for the buses are not convenient and its a little too far and hilly to bike normally. To get across lake Washington and make it tolerable the mountain bike was going to need a little help.

So I decided to add an electric motor.

I ordered a hub motor kit and battery from Ebay with the goal of converting the bike into an e-bike that will make it easier to go long distances and to chew up all the hills in the way. But ordering a lot of electronics parts from china means they don’t come with very clear instructions.

The bike is still mostly in working condition. There was just one small broken plastic ring in the handlebar headset that had been keeping it off the streets. Bike shop wasn’t sure it would be able to source the part and wanted to replace the entire headset.

A small piece of plastic, why not just 3D print it?

I didn’t print this piece myself. I outsourced it to a friend who could print it in high performance PETG plastic so the ring would be flexible and durable. It took a couple of tries to get the fit exactly right.

Before mounting 20 lbs of electronics to the bike I needed to test to make sure everything was working. I temporarily mounted the new front wheel without tube or tire and hooked it up to the pile of cables on the ground.

Glad to say everything was working properly.

In attaching all the electrics to the bike I did encounter one expected problem. As a safety feature, the brake leavers needed to be replaced with leavers that have integrated electric switches which will serve as emergency power cut offs for the motor, so it can never accelerate while the brake is down. This Trek bike has integrated brake leaver and gear sifters on the handlebars, so I can’t replace the brakes without losing control of my gears. So instead of mounting the new brake leavers I went with magnetic switches attached to existing brake system.

There was still a lot more that needed to be done, but with everything critical bake in place and the electrics working I had to have it out for a test ride.

The test ride was a success though a little wobbly. I found that there were a lot of things to tighten down and that the front tire was not sitting completely evenly.

The electronic cut off brakes were working, but I wasn’t happy with the physical brakes. Unfortunately this bike cannot fit disk brakes, but I replaced the old brake pads with new larger ones and tuned up the whole system.

There are still a lot of improvements I would like to make, integrated front and rear lights, better cable management and housing for the speed controller, a speedometer and control display, and maybe even a more conformable seat. Its serviceable as it is and I have all winter keep making improvements.