[python] Re: PX.5 report

At 09:07 PM 3/9/2005 +0100, you wrote: 
Today I finished PX.5:

  Pivot angle: 63 deg
  Trail: -47 cm
  Seat height: 33 cm
  Wheelbase: 118.5 cm
  Clearance: 11 cm


good to hear!

This reminded me of a balance where a minimum change of
weight decides on equilibrium or mismatch.

Now, here a formula would be very helpful.

I was working on something just like that after your last email. It would compare the potential energy change (due to delta-height when turning) of the falling front and rising rear masses. If they are reasonably balanced, they should offset.
I need to review my code, as I still disagree with Dirk's results on rear mass rise.

Your experiment helps give the effective placement of the front mass; I see that as the hardest thing to estimate, since riders span the front and rear with their legs.

Here the stability program of Ray cannot help because it does not
consider the dynamic perturbation of pedalling legs.

The equations are designed to show whether the oscillations due to a sudden small bump or wind gust will die out or get worse. A large rhythmic movement is a bit different.
Which reminds me, what is the feel when not pedaling ? Do you steer by legs or leaning? Do you initiate a left turn by a small right turn, as uprights do? A video from the exact front of a rider would be interesting in slo-mo.

Anyway - tomorrow I will make PX.5 ready for the road and
start the high speed testing this weekend as the snow is melting
away rapidly (finally!).

Picture of PX.5 on the mod page:
http://www.python.tieflieger.net/pics/Python%20PX.5.jpg

It will be good to hear your opinion of the extreme rear placement of the pivot vs. the shorter trail models.

Ray

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