It’s tough to find high-quality 20” wheels suitable for mini-velos / cargo bikes. The offerings I found were either very expensive or built with bmx hubs (no disc brake, thru-axle).
I built a simple sturdy pair of wheels with the following specs:
Rims: Promax RMV 20” Tubeless-Ready 36h
Spokes: Empire BMX 14g
Nipples: DT Swiss 14g Brass
Rear Hub: Shimano 105 142x12 36h (Centerlock Brake)
Front Hub: Shimano Metrea Dynamo 36h 100xQR (Centerlock Brake)
Truckster is a short, simple project to explore some new fabrication methods and resources.
Dropouts and small parts are 3D-printed 316L from JLCPCB.
All tubes are 4130 from Wick’s Aircraft and McMaster-Carr and laser-mitered by Precision Tube Laser in Nevada.
Ride Report:
I’ve been riding Truckster for several months now. I love the way the bike handles. It’s a perfect nimble commuter bike and comfortable enough for longer touring rides and suffer-fest climbs. I’m a convert for mini velo utility bikes and will be exploring this space in future builds. I’ve summarized some of my thoughts below:
Works well:
Comfortable, upright seating position. I used the Velo Orange Nuetrino (L size) as inspiration to set my geometry numbers. This works very well for me (5’10”, 32/33” inseam)
3D printed dropouts and yoke. So many fabrication possibilities have been opened up through 3D printing. I love the ability to create geometry-specific components that make the frame fabrication process easier and more resistant to mistakes.
Front-load area: I used M6 bosses to mount a Wald 157 basket (and now HDX 17-gal tote). The bike handles well with 20-30lbs in the front.
Laser-cut tubing: Gamechanger for framebuilding! The ability to create precision, laser-cut frame tubes is incredible.
What I’d change for next time:
Steering wobble: For the first month or two, the fork would occasionally “shimmy” if I took my hands off the handlebars. This behavior seemed independent of headset preload (within reason) and front cargo load. However, this went away over time and the bike is now incredibly stable. I can ride it without hands at 5mph and 30mph.
Slightly shorter cranks. My BB height is around 275mm with 2.4” tires. I pedal strike fairly regularly with 170mm cranks. This is mostly a skill issue :D, but I’d like to increase the BB height to around 280-285mm for my next bike(s) and perhaps run shorter cranks.
Tube bending! Future builds will use laser-cut tubing and tube bending (I bought a Toob bender from Joe).
