Hi Jürgen,
OK, we should advertise the pushable requirement, perhaps in the pivot
angle page. I tested pushing the bike on concrete surface today, and
it's not very easy to maintain a straight line for long.
Yes, DirkB's website <http://dirkb.dnsalias.net/python.html> recently
came back online, so I was able to download the program to play with.
It must be a newer version
<http://dirkb.dnsalias.net/pythonselfcenterprogram.html>because it is
now written in C# and compiled for Windows (exe). Luckily, I can
compile and run in Linux MonoDevelop. It would be nice to do some
dynamics simulation of stable and unstable settings/conditions.
Experimental measurements would be good also, say gyroscope and
accelerometer (iPhone).
Regarding wheel flop, my BB is very close to the hub so the impact of
long wheel base seems not as much as pivot angle. I was eager to
learn some more today. I can turn left / right with just a touch of
my glove on the ground for assurance, and learned to push harder on
the pedal to get back in line.
Went over road bumps and speed bumps also, so 20in wheel seems OK.
Will do off-road test this weekend. Good seat contact seems crucial
for controlling the bike, the arms also. Funny how the training
wheels now give me less control than free arms, so it can be retired.
Maybe there is an invisible handlebar somewhere (quantum?). The
gloves however are very useful, not sure when they can come off.
Thanks for the advice and safety concerns. In general, I am afraid to
be in traffic on any bike, not to mention this one, so I will stick to
empty streets, curbs, and trails...
Vi
------------------------------------------------------------------------
*From:* Jürgen Mages <jmages@xxxxxx>
*To:* python@xxxxxxxxxxxxx
*Sent:* Wed, March 16, 2011 1:49:52 AM
*Subject:* [python] Re: Cool handlebar for 48deg 20in
Great!
The last seconds of your video shows something essential: If the
python is pushable it also is rideable.
Also great to see that you have used Dirk Bonnés calculation program,
which funnily enough is written in the programming language python:
http://en.openbike.org/wiki/File:GuineaPigPivotAngle.png
But also keep in mind, that the combination of pivot angle and weight
distribution is crucial for rideability. A heavy front part needs
bigger pivot angles for wheel flop compensation.
And lastly keep in mind that it takes several hundred kilometers of
practice to feel save in traffic ;-)
Cheers,
Jürgen.
On 16.03.2011 03:10, Vi Vuong wrote:
> Magic, I can ride it on first trial :) Ground clearance also
improved, but seat angle became a little too upright ~40 deg to stop
me from sliding off forward. I can also push it forward by the
headrest. Perhaps this is a good objective test for ride-ability,
independent of hip coordination...
http://www.youtube.com/watch?v=6yBjSGL_pd8
>
> Vi
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