The most persistent problem with the Kalamazoo has been the temperamental drive. Every stroke of the pump lever would result in a terrible clank, and it was very hard to keep the thing moving. You had to time your pumps exactly right, while not applying any force at the top and bottom of the stroke. That is why one of the first things I did this year was cut the decking to allow for much longer arms on the simple flywheel hack. That helped, but a greater flywheel effects was needed.
This is what I came up with, a welded hexagonal ring. It's made out of two sections which bolt together, which allows it to be mounted without having to remove the crankshaft. Lead weights are then bolted to the ring to increase its rotational inertia.
About a week after finishing it, we finally got around to running a full roadtest using it, with very positive results.
The Kalamazoo is finally handling as I had always imagined, though it's still very slow. Carrying passengers worked well and made the motion even nicer. We've found that having a secondary driver in the forward position doesn't help very much. Synchronizing pumping between people turns out to be a difficult thing. I'm thinking of adding an unpowered dummy in the front position, but I probably won't get to that.
I'm now working on casting the lead weights into a more conformal shape which will allow them to be mounted on the outside of the wheel. This should be both more efficient and more aesthetically pleasing.