Technical Research: Steering Geometry

In 2006 a recumbent builder in the U.K. sent an e-mail suggesting the rake (steering angle) of my front suspension was too shallow and the steering would be heavy, especially at low speeds. He said the rake should be steeper, more like a sportbike instead of the chopper style I wanted. Having owned both bikes at right, I agree the chopper needed a firm hand when making slow turns, but in some situations it was more fun to ride than the Interceptor.

Even though I had previously done research regarding rake & trail, I tackled it from a different perspective. I found some information on rake, with Tony Foale's site standing out from the rest, but there is surprising little to read regarding trail and virtually nothing on the relationship with rake. The big manufacturers have such data because they spent the time and money on research for their type of bikes, but why should they publish it on the web for free?

Rather than proceed blindly, I built the Test Mule to try different combinations of rake & trail and measure the effort required to turn the front wheel. As it turns out, the tests showed a steeper steering angle works better. All of the steering combinations worked in one way or another, but some were clearly better. In the end I had to chose one and I'll see if I'm happy with it. If not, at least I have a starting point and I'll know what changes to make.

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