A few years ago, I built a cargo trike. I was seduced by the formula, and wanted one. Of course I've found good reasons to justify it, like using it as an itinerant photo lab. Or go shopping. Or carry things when going for a ride.
I've loved using it, but it was not as practical as I thought. It's heavy, and it needs a lot of space to sleep.
So I decided to sell it, and last tuesday it has gone. Soon it will help someone to sell flowers on a market.
The donor fame being chosen, half of the geometry is settled. Then comes the time of choices. What length do I need, or want, for the cargo bay ? What width ? Do I want to go easy with a large, straight central beam and secondary beams on the side ? Or should I build something a bit more complex with two beams on sides, and spars in between ?
... is to find donor bikes. Two are needed. One with 26" wheels for the rear frame, and one with 20" wheels for the fork and front wheel. Almost all cargo bikes available and self-made use these sizes. On the trike I had a 700 wheel at the back, and two 26" at the front, and it was a bit to high, thus less stable.
I've tried too find an electric bike for the rear frame, that would have been nice to go with a motor from the beginning to help, but every bike I found used was made with aluminium frame, that most people (including me) cannot solder. So the next choice is to use a mountain bike, which is made to be strong. On this bike we keep the rear wheel, the crank, the frame, the direction pivot, the saddle.
The second bike is for the front pivot, the fork and wheel. With a 20" wheel, the obvious choice is a BMX, which are strong bike too.
It has been a relatively quick project, but ambitious one for me, as I had never worked with steel before. Fortunately, my sister's husband was a metal worker, and showed me how to use MIG, and let me use their professional gears...