[python] Re: Human power article
- From: Dirk Bonné <dirk.bonne@xxxxxxx>
- To: python@xxxxxxxxxxxxx
- Date: Thu, 23 Apr 2009 22:05:32 +0200
Hello Bill,
Just some comments from my part:
The advantage I can see with self centering that the wheel flop is gone.
I have never ever experienced the presumed disadvantage of instability,
and I have several >20000km on my bike. Max speed has been 66km/h (I
take what I can get), but I am confident that more would be no problem
at all if the opportunity presents itself. Min speed is 6kmh on flat,
below that it gets difficult.
The strength of self centering doesn't matter for stability. But self
centering changes the style of the bike a lot:
* With little self centering you get a next to neutral steering, and by
this an agile bike.
* Strong self centering gives the limousine feeling: maneuvering takes
a lot of effort to turn the front part.
As the trail directly correlates with the wheel size (see survey on
http://en.openbike.org/wiki/Python_Projects_Survey ), you will see that
the style of the bike is determined by the wheel size. Exaggerated: bike
like the "monty" (16") can turn on a coin, whereas the "birdcage" (26")
you need a run around the block to turn (I have ridden both).
best regards,
Dirk - baby python
Bill Patterson wrote:
> Hello Jurgen,
>
> Thank you so much for your quick reply. Your geometry url below was
> very instructive.
>
> The concept of seat rise is exactly the same thing as K1 in my
> handling qualities theory. For a normal geometry it causes a low speed
> wobble, but for your geometry it causes the seat to fall. This
> generates a strong centering spring at low speed. Wonderful idea.
>
> I must admit that I was appalled at building any negative trail bike.
> I was wrong.
>
> I have been asked to help with the technical side of Human Power and
> feel that the Python design process along with rider comments would
> make a welcome subject for us. The theory on the URL will round out
> the paper nicely. We might need a list of background references.
> \
>
> Bill Patterson
>
>
>
>
> Hello Bill,
>
>
> Writing an article for the HP magazine is not chicken-feed. Could you
> please outline what you expect?
>
> Lots of material can be found here:
>
> http://www.python-lowracer.de/geometry.html
> http://dirkb.dnsalias.net/pythonselfcenter.html
>
> Also our small communitiy could provide lots of pictures and videos.
>
> Regards,
> Jürgen.
>
>
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