Leaning cargo trike build log

Hey all, I figured now is a good time to share the leaning cargo trike I’ve been working on. I have been stoked on cargo bikes for many years now, especially after becoming a dad and transporting my kid on a yuba long tail every day for the last 5 years. About a year ago, I was nearly done building a custom 4130 bakfiets when my wife crashed the Yuba on an icy road (thankfully after dropping off the kiddo). She was scared to ride for a while after that and I realized that a huge barrier to many people feeling safe on the roads (besides the poor bike infrastructure in the US) was the stability on slippery surfaces. Hence the leaning trike. I decided a steel trike would be far too heavy, so I decided to complicate the build even more by using aluminum. I have more than 50 steel fillet brazed bikes under my belt (well, I did 20 years ago), so this was a new challenge, having never welded aluminum before. This whole description is going longer than expected, so here are some pictures.

Why a leaning trike? Well, if you’ve ever ridden a non-leaning trike around a corner at more than walking speed, you’ll know. Or ridden on an off-camber road. I also wanted to keep the width around 24" so that it can fit wherever a bike can go, more or less.

I should mention that even before my wife dumped the Yuba, I was messing around with trikes. I bought a trike conversion front end from a guy in Taiwan that was posting on Endless Sphere : https://endless-sphere.com/sphere/threads/leaning-trike-cargo-bike-front-end-kit.86613/
Despite some shortcomings, I was amazed at how well it behaved, and acted like a bike.


First of many challenges was tube bending. Here is a modified JD2 with a mandrel. The bent tubes are 7005 38mmx1.6. I annealed them using the ol’ candle soot and torch method.

It took many attempts. Some of which are detailed here:
Swingarm was CNC’d 2 pieces from one of the many amazing CNC shops in Shenzhen. I have no idea how they do such an amazing job for so little.
Wishbones were made from 4130 and DMLS yokes (as is all the rage these days).

Practiced my TIG for a few hours a week for a while then finally tackled the main frame

The tight angle on this joint warped considerably, reducing my seat angle a few degrees :sob:

But all in all, it turned out ok considering the challenges. The electrical system is the next step. I chose all standard off-the-shelf components for this build. I went with a direct drive hub motor (Grin All Axle) because after riding a cargo bike with regenerative braking, it’s really hard to go back to friction brakes.


The build is coming along, and the bike is rideable and actually exceeds expectations. Handles very much like a bike, with that extra bit of stability of the extra wheel up front. I’ll hopefully ride it up to the snow line to see how it handles snow soon. I still have a bunch of work to do for lighting, tilt lock, cargo box, kids seat, etc, etc, etc.