DIY Cargo Bike Progress
Seeing as I used to be an engineer, I decided to have a go. First up, I sourced a couple of suitable steel frames and some plastic tubs to help me size up the cargo box:
I chopped them up:
Got myself some steel stock & some weekend time with a friend who’s a qualified welder. Unlike Tom’s original design, I opted for box-section rather than round tubes:
The beast looked BIG while it was being welded up…
… and even bigger on the floor:
We’re almost finished now - yes those are the original handlebars from the BMX bike being used as the prop stand:
Detail of the steering linkage - we had to add a couple of stops either side of the head-tube, otherwise the steering could become unstable & lock in the 90º position, which would NOT be good!
Initial test rides in the garage show that the frame geometry is basically stable (can be steered no-handed), and despite the length (nearly 3m long, with the cargo box’s base being 85cm long), the turning circle isn’t too bad - around 6.5m. OK, so that’s a LOT more than the Brompton’s 1.2m, but this really isn’t a nipping-through-the-traffic kind of bike.
Surprisingly, it doesn’t weigh that much more than the original mountain bike did - probably just a couple of kilos, and most of that is in the extended rear head-tube.
Things left to do:
- Cap off the sawn sections of the BMX’s frame & fettle up the more agricultural welds
- Add brackets for the box
- Sort out the prop stand’s spring so that it’ll stay in the up position
- Paint the frame
- Build & fit the box
- Fit the missing components - a taller quill stem, brakes, pedals, gears, etc.
- Go out frightening the traffic