Cim’s Cargo Bike

If we’re being honest, a custom bike is a “nice to have” and not a necessity for most folks. For really, really tall folks like Cims though, a custom frame is needed to get anything approaching a proper fit without a bunch of compromises and kludges. What’s more, Cims needed a bike that could haul a lot of weight not just on the frame, but on a trailer for his sustainability work.

I’ve known Cims a while, and in that time I’ve lost track of how many mass produced frames marketed as “indestructible” he’s pushed past the point of failure in the course of his work hauling recyclables around town. When he asked me to build him a purpose-built frame I knew I had a challenge ahead of me.

The first step was getting Cims a proper bike fit to define the overall shape of the frame. I had a pretty good idea what geometry would work best with the drop bars he wanted to run, but the stack and reach figures (vertical and horizontal distance from the bottom bracket to the top of the headtube, roughly) were well outside what could be served by off the shelf frame parts.

Steering the hundreds of pounds of cargo this frame would carry called for a steel fork with a tapered steerer - overkill for most single frames but perfect for this application. I was able to find one such steerer tube on the market, and it had just enough length at 450mm (that’s looong) to get the bars level with the saddle as suggested by the fit data.

My fellow builders have probably done the math already and found as I did that there aren’t any machined 44mm head tubes long enough for this steerer. Instead I got some 44mm straight headtube stock and cut a 300mm (also looong) section out, which I brazed some thick reinforcing rings on to.

With the front end sorted, another challenge arose in the front triangle. It’s called a triangle traditionally, but if you look at a frame you can see it’s really more like a parallelogram. The long head tube and seat tube of this frame enhanced that shape, and I could tell just by looking at the drawing that it would ride like a noodle when loaded no matter how large I made the main tubes.

I’ve always wanted to build a cycle truck, a style of cargo bike that traditionally uses a smaller front wheel to allow for a steering-independent platform welded into the front triangle and projecting over the front wheel. With this frame I realized that even with drop bars there was enough space between the bars and the regular-sized front wheel for a small platform and a basket. The support members for the basket connect the bottom of the headtube to the top of the seat tube and greatly increase the lateral stiffness of the frame.

That left the rear triangle, where most of the frames Cims has done in failed. Hauling a trailer puts a huge amount of stress on the chainstays, to say nothing for the pedaling forces of a strong, tall rider. To counter these forces and reinforce the whole area I used 1.125” fork blades for chainstays, which are much larger and thicker than off-the shelf stays. The blade-stays are joined by a welded lower kickstand plate with a CNC’d top plate to properly distribute the forces.

I used my standard UDH dropouts for easy hanger sourcing, but substituted 304 stainless steel for 7075 aluminum when machining the brake mount for added stiffness. A tubular brace also connects the chain and seat stays to help dissipate braking and trailer forces. The trailer itself attaches via a custom hitch mounted on a Robert Axle Project trailer axle. This is much cleaner and stronger than the universal hitch that was attached to the previous bikes with pipe clamps.

While the frame had several features designed to deal with the rigors of this application, the bike wouldn’t be up to the task without an appropriate array of components. The rear hub is a DT Swiss Hybrid hub, with thicker spoke flanges and a steel freehub, designed for e-MTB use but just as useful for a cargo bike. The front hub us a Shutter Precision dynamo hub, which powers Supernova front and rear lights. Both hubs were laced to bomb-proof Astral Outback rims with DT’s burliest spoke, the Alpine III.

I’m not really a Shimano guy, but I had heard and seen good things about the new CUES drivetrain with Linkglide. With the stated goals of durability and ease of maintenance being top-of-mind, CUES was the natural choice - and it even played well with Cim’s preferred bar-end shifter. Without any need for the brake levers to handle shifting, I was able to link the classy and functional TRP RRL levers to their Spyre brakes and larger rotors for powerful braking without the fuss of hydro.

Cims brought a rear rack and fenders to the build, and I supplied the oversize Wald basket attached with custom brackets to keep everything in place. One last detail specific to this bike’s application is the addition of front and rear frame locks. Rare outside of the EU, these allow the rider to immobilize the front and rear wheel so the bike cant be ridden or rolled away. Cims does a lot of quick trips in and out of buildings in his work, so this will be much faster than getting out multiple U-locks and finding something to lock the bike to. In theory someone could still pick up the bike, but with hundreds of pounds of cargo they wouldn’t get very far.