New electric bike drive-train

I’ve started work on the new version of Deathtrap, my electric bike project. The new bike is aptly called Deathtrap2 🙂

The video shows progress so far. I’ve designed and built the main structure and drivetrain. Even going so far as to test it!

For the new version I have switched from a 25H chain to a 08B 1/2″ roller chain. The goal of this version is to do things properly and robustly, hopefully this way over-spec chain will help achieve that.

To start the main bike frame was put into SolidWorks. From there the full system was designed.

Before committing to the design I laser cut the side plates just to test the fit. This worked out well and I was satisfied everything would align.

Now, on to fabrication.

To start I tackled the rear sprocket. There was no light-weight sprocket of the correct size for the 08B chain I wanted to use. I ended up just designing and machining my own sprocket from aluminium.

Spurred on from the success of the rear sprocket I started work on the lay-shaft.

The original design called for a stainless steel shaft. I ended up using aluminium since I didn’t have any stainless readily available. I hope this does not come back to bite me.

Next were the two side plates. These were machined from 10mm aluminium plate.

The first side came out perfectly, even the bearing fit gave me no troubles.

Not pictured is the modification of the sprockets. I ended up getting a broach set specifically just to make the key-ways for the sprockets. These came out perfectly, money well spent.

A problem of the last design was the non-sensored motor. This gave very poor performance at low RPM and made it impossible to start from stationary. To fix this I’ve added hall sensors to the new version. I actually couldn’t fit them inside so they are mounted externally on the frame.

Everything ended up fitting perfectly. Very satisfying.

Finally it was time to test. My custom sprocket would need a relatively large amount of breaking in so I let it run for a while with no load and plenty of lubricant.

See the video at the top for this.

The final product will be fully enclosed, but I’ll add that once the electronics and other components are all in.

Next will be the electronics…