[python] Re: Jetstream

  • From: Dirk Steuwer <dirk@xxxxxxxxxx>
  • To: python@xxxxxxxxxxxxx
  • Date: Wed, 28 Feb 2007 20:33:17 +0100

Am Mittwoch 28 Februar 2007 19:38 schrieb Stephan Schöling:
> It took over 1 hour to read that ;-)
it really does ;-)
> May i try to summarize with easy words, please correct me if i'm wrong.
> The frame itself isn't stable, the frontpart flops sideway (by gravity).
> The self-centering effect works against that, is making the bike stable.
> If I put some weight to the seat (gravity too), i increase the
> self-centering effect.
> My python frame (without rider) balances at ca. 8 kg on the Seat.
> (Borderline between the two effects)
> The riders weight increases the self-centering effect.
> The pivot angle decrease: increase wheel flop, increase self centering
> (up to a point). (we still have to find the proportion)
> neg trail increase: probably not much influence on wheel flop, increase
> self centering.
> Luggage placed near the rear wheel doesn't have much effect to the
> stability of the bike, because its away from the SBB.
> Dirk:
> You wrote, your formulas are wrong ?
> What is wrong with them ?
> Stephan

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 
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.

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


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