After handing off Ben's bike in December, I started work on a very different project. Boson got hold of me looking for a bakfiets style cargo bike based off of two donor bikes. As it happens, my friend Jake over in Portland, OR (http://www.jrydevisuals.com) has done a couple of these projects, so I had a couple of ideas going into it on how I might best proceed. I based my bike on Josh Muir's Smallhaul (http://www.francescycles.com), which I have always admired in theory and in person. My approach takes the best features of a very cool design keeps the price down and simplifies the construction a lot by using a donor bike for the rear end of the vehicle. Boson tracked down an older Specialized Hardrock Sport frame to use for the back end. Here are my sketches:
I start all my projects with a 1:4 scale drawing. Here, you can see I began by measuring and drawing the donor rear frame, and then built the framework of the cargo bay and steering assembly up front. Often as I move from the drawings to the fabrication itself, I will revise small details, but all the big features are nailed down here. The front wheel will be connected to the handlebar steerer tube by a crafty cable system routed along the top rails (not pictured yet!). The cargo bed is the lowest point on the bike so that the whole thing has as low a center of mass as possible while still retaining cornering and curb clearance. The front head tube, the point at which the bike steers, sets up the small (20") front wheel with a lower than average trail to keep the bike steady at low speeds under load. The front fork is a stock fork, which also helps keep the production simple and the costs down. The cargo bay flares upwards, wider at the top than at the bottom, to allow for additional space within. The rear of the bike retains the ability to mount a rack with panniers as well, which gives the whole bike plenty of capacity for a child seat and groceries as needed. The tubing is straight gauge chromoly, study enough for a heavy load, but not so overbuilt as to make the bike cumbersome and a drag to ride around. Boson is planning to build the bike up with cable disc brakes and a dynamo powered lighting system for practicality and durability. The actual sides and floor of the bay will be made of thin plywood cut to fit.
Construction is well underway, and I will post some more construction pictures soon!