[python] Re: Jetstream

  • From: Henry Thomas <whpthomas@xxxxxxxxx>
  • To: python@xxxxxxxxxxxxx
  • Date: Thu, 01 Mar 2007 06:51:32 +1000

Dirk Steuwer wrote:
I have a "feeling" that the wheight/distance in front of the contact point of "frontwheel and ground" in relation to the wheight/distance behind this contact point to the BB playes some role in this. I imagine that when you push the right pedal, the python revolves around the ground contact point to the left, while BB moves out to the right. Then the centering effect tries to rectify this. If the trail is bigger, the "leaver" of the centering effect is bigger, than that of your foot pushing the front end. If you can follow my theory, a python with its front wheel closer to your pedals should behave better, that one with the same front section, but the wheel closer to BB.
So it would seem that we probably need a theory here much like the A > B equals wheel flop, A == B is in equilibrium, A < B self centering force becomes stronger. But from where should we measure A and B, and how should they relate to the pivot angle.

It would seem that there is a relationship between trail and seat height. T > SH is less stable, T == SH is better, T < SH is best.

Heuristics like these, as long as they have some basis in an observed phenomenon, are really helpful, given the degree of confusion that still exists. Almost sounds to me that we have a engineering thesis project here just waiting for someone to discover it.

What would happen, if you were to pedal in the center of the front wheel, like those old "penny-farthing" cycles?

I have a picture of such a bike (attached) that appears to work as you describe here - but I don't know much about its origins or history.

-h

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