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What I've been up to lately
By Charles Brown
Editor's note: Charles Brown wrote this prior to the Michigan HPV Rally, which he attended. For those of you who don't know Charles, he and his wife, Blue, moved from Ann Arbor to Clearwater, Fla., in 1994. He's built more recumbents out of wood than anybody and is a frequent contributor to human power publications.
There's a lot of projects going on around here. I built a front-suspension bicycle to see if one can be built that is not actuated by pedaling forces. I concluded that the natural frequency of the suspension should be outside the normal range of pedal pushes per minute (2 x the crank's rpm) and the suspension should be well dampened.
Another experiment was to build a bike with a steering system utilizing a universal joint, like Mochet's Velocar from the 1930s or the Ground Hugger recumbent (the subject of a how-to-build article in Popular Mechanics in April 1969).
Using automotive driveshaft bearings, I got a lot of lost motion or slop in the steering system. I've since learned from the Internet and Gunnar Fehlau's book, "The Recumbent Bicycle," that other people who tried U-joint steering had the same problem. I'll go back to using a push-pull rod next time, where I had the same difficulty in the past, only this time I'll use aircraft rod end bearing, such as Wicks Aircraft Supply sells, which I understand are a lot better. (Editor's note: But at the Michigan HPV Rally, Charles saw one or two -- I forget -- homebuilts that used a U-joint in the steering and had little or no play in the steering. Apparently it's a matter of buying the right U-joint.)
In every way but the steering, my Velocar clone is an exceptional bike. Mochet was really ahead of his time.
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Got a letter from Vernon Forbes, the new editor of Human Power (published by the Human Powered Vehicle Association). He was spending the spring in St. Petersburg, just south of me, and invited me down to say "hi."
I met an extraordinary human being, driven more by principles than money. He is incredibly well educated, but fixes bicycles in a shop.
He became editor partially to get his own material published. His own interests lie in the esoteric, pure science end of the bike world. He said he has enough articles to fill four more issues. I'm building my first bikes with really laid-back seats. These really do reduce the air drag. I bicycle to work 8-10 percent faster than I use to.
I tried painting one of my bikes with glow-in-the-dark paint, but it has to be really dark to see it. With street lights, automobile headlights and bike lights, you don't even notice the ghostly glow. I've seen reflective tape for sale that might be something better to cover a bike frame with.
Currently I'm trying to design a safer cycle. Any protection from cars is better than what I've got now. My current thinking is a sort of a full body helmet with three or four wheels. Does anybody have any ideas?
Handlebars are again being tinkered with. I'm again amazed how rather small changes to the bars can greatly affect steering and how pleasant the bike is to ride.
In my opinion, for a supine recumbent, measuring to the center of the handgrips, the distance of the handgrips back from the steering axis should be 25-40 percent of the distance between the hands. I'm also working on a short wheelbase bike with a rider position like a (dual big wheel) Bachetta, but with the rider lowered 4 inches due to use of a 20-inch front wheel. I think this design shows some real promise.
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