Fork

I welded most of the fork today. I still need to braze the top of the crown race, cap the fork blades, and braze on the internal dynamo port.

Welding the dropouts was my first time working with 3D printed parts. The dropouts welded a lot like cast parts - no surprise here. I used Weldmold 880 (similar to ER312). Welding this butt joint was pretty tricky for me and I wasn’t able to maintain a very consistent bead. Something to work on for next time!

I’m pleased with the overall aesthetics of the fork. My optical table based fixture worked well - I reamed out the “6mm” holes as the diameter created by my 3D printer (Bambu X1c) were slightly undersized and caused binding. Reaming was the right choice - so much easier!

Colin ReayApril 1, 2024

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).