E Bike Conversion With Side Car

We were headed to Burning Man this year and my wife said she was looking for an easy way to get around. Its pretty easy to just ride a bike around (its a dry lake and totally flat) and I thought of Ebikes and remembered a picture of a bike with a side car on it. I figured I could kill two birds with one stone and build a E Bike with a side car on it.

I had a cruiser bike that years ago I had put a 50cc gas engine into, the bike had been setting around for at least 10 years so I figured it was time to let it have a new life. I had just moved into a new place, had to set the garage up and had about 2 months (along with moving in) to complete this project.

I've got another Instructable that I did a E Bike conversion on so I was familiar with putting one of these types of projects together.

My previous project already is using a 52v 20ah battery so I figured I would get the same size battery again. I figured I could run two batteries in the side car project - since I had no idea how far the finished project would go on a single battery. So I got a 1000w 48v rear hub motor and run it with 52v like my other project.

I would of liked to go with a wider rear tire but the frame spacing didn't allow for it so I was stuck with the skinner 26" rim. I could of went down the rabbit hole and got a wider rim and re-strung the wheel, but as mentioned above, I had a lot of things going on, time-wise and didn't have the time to pursue this.

I went through dozens of pictures of motorcycles with side cars on them and as much as I like that old school zeppelin formed aluminum nose for the side car, I also knew that was beyond my skill set and the amount of time I had to put this together.

So I had the cruiser bike, an old 1939 Ford truck grill and a old motorcycle fender laying around and decided to incorporate the grill and fender into the project.

No design really at all, just winging the whole thing. From the pictures I did some mockup and sizing of how big I wanted it all to be.

I took into consideration:

NOT forgetting to be able to turn the front fork left and not run into the side car.

I wanted a space for a cooler in the back.

Having it big enough to fit an adult but not any bigger or heavier than necessary.

The bike only needed to go - maybe - 10mph tops so it didn't need any aerodynamic skinning or anything like that.

Suspension for the 3rd wheel would be nice but it would take longer to build.

I wanted it to be very easy to get into and out of and comfortable enough that you could ride in it for a couple of hours.

The side car has to be easily detachable from the bicycle because we had to break it down and put it in a trailer we were towing to the event where it would be put back together, then disassembled to take back home.

The frame has a very large area behind the seat tube and rear wheel. I figured I would start with a 3"x1" beam bolted to a 3/16" plate I welded to the frame as a foundation for the side car.

From there, I used CAD - cardboard aided design to figure out what the basic frame would look like.

So the flat frame probably wasn't strong enough even with the struts from the bicycle frame to support an adult without bending. So I boxed the frame and started making the struts from the bicycle frame. Since I had to be able to break it down to get it to the event then put it back together, I used some heim joints and tabs from another project. I brazed the tabs onto the bike frame and use the weld bungs that fit into 7/8" tubing for the struts.

Having no idea how strong this needed to be I - despite trying to save weight - added as many struts as I could make fit on the frame.

For bending the tubing I purchased a hydraulic pipe bender for the bends. The bends - well I'm not proud of them but I got it done. I need to get a proper tube bender one of these days.

So once the frame was what I thought structurally complete, I started added on the extra bits. The mounts for the grill, how the seat was going to mount, struts for the back of the frame for the cooler.

For the axle, I had originally wanted to go with just a single mount for the axle from the frame. The axle is 10mm and I foolishly thought that would work. Well it didn't it bent just when I was working on the frame.

Fortunately I had a old full size cruiser bike fork laying around so I cut it in half and mounted and gusseted it onto the frame (more weight.. I was getting worried).

For the floor board I went with expanded metal (metal grate) cut and welded that onto the bottom of the frame. Had to weld it enough so an adult could stand on it and not have it break off.

At this point the initial metal work was done. I could ride the bike around some with a adult in it and it seemed to hold up. An adult could also stand up in the frame and not bend or break the frame off.

So from the previous build I had a motor mount to hold the 50cc gas engine. I embedded the motor controller below that area and did some wire clean up.

I also build the battery box out of some old press-board furniture and used an old yoga mat for padding.

I put in a master battery cut off just because I wanted one.

I did not put the batteries in parallel, I kept it simple and figured If I ran one battery down I would just remove the seat and connect the other one.

I don't have any pictures of this!

I wanted a isolated flat road that I could test the bike out on. I wanted to be able to run the bike a mile straight without stopping so so I could get an idea of battery life.

I live in a hilly area and knew from a couple of quick tests that the bike, sidecar and me can't pull a very steep hill without pedaling let alone another person. I found a long stretch of road, brought my brother with me and went for a test drive.

We did 1 mile straight ahead runs at about 7mph. Back and forth until the battery was dead.

I was able to get 10-11 miles on one charge, with easy starts, (easy acceleration - no pedal assist) keeping the speed between 5-8 mph. The bike did a excellent job, easy to drive, easy to stop, didn't break or bend, didn't smoke any of the electronics, all good! Hit a couple of bumps and the 3rd wheel didn't bend or twist.

What we did find out is that we needed to add a fender on the 3rd wheel. The rider doesn't have any place to put their arm. I was planning on doing this but didn't get to when testing. I also had to make a padded seat (had that planned too) to make the ride more comfortable.

The seat was made of some old press board furturniture with a yoga mate for padding. Picked up a yard of fabric and basically just spray glued the fabric to the wood. Tried using a stapler but it didn't work.

The bike worked perfect for the days we were at Burning Man! We got a lot of people checking it out and taking pictures. Turns out 10 miles driving was about the time we would spend checking things out things during the day, and about the same time at night. I never had to switch packs out but having the 2nd pack was a nice backup incase we did. No connection or electronic failures, I didn't have to put a wrench on it the whole time!

Things we will change/improve/notes

The fender needs padding. It was 100+ most days and you couldn't put your arm on the fender because it was too hot to touch.

5-7 mph is the perfect speed. The speed limit at Burning Man is 5mph. Which a lot of E Bikers didn't obey at all.

A regen feature on the controller would be nice.

The roads in the camps were in really bad shape. A suspension on the 3rd wheel would be nice. The front fork is a suspension fork and it really got a lot of use on the wash board roads.

Maybe a 2nd layer of padding on the seat - just in the camp area because of the roads.

Re-string the rear wheel and get a wider rim. Just a visual thing. I had thought that the bigger tire on the skinny rim with all of the bouncing would cause a blow out - didn't happen!

I over built this. I used 1" square tubing, and the 3"x1" beam for support. I could of used 1/2" tubing and in place of the 3"x1" beam just used another strut. Could of save quite a bit of weight.