[python] pushable/ rideable
- From: "Gerald Kuettner"<bepb@xxxxxx>
- To: python@xxxxxxxxxxxxx
- Date: Fri, 18 Mar 2011 15:18:08 +0100
-----Ursprüngliche Nachricht-----
Von: Vi Vuong <vi_vuong@xxxxxxxxx>
An: python@xxxxxxxxxxxxx
Gesendet: Fr., 18. Mär 2011, 06:33:20 GMT+00:00
Betreff: [python] Re: Cool handlebar for 48deg 20in
Hi Gerald,
Some weight on the seat / pivot is reasonable, but the push method seems to be
more objective than riding, which heavily depended on individual coordination /
experience. My left turn seems to be much smoother than my right turn, brain
issue?
Vi
________________________________
From: Gerald <bepb@xxxxxx>
To: python@xxxxxxxxxxxxx
Sent: Thu, March 17, 2011 10:24:07 PM
Subject: [python] Re: Cool handlebar for 48deg 20in
Hi Vi, Hi Jürgen,
I am not sure about the pushable requirement. Maybe a python beeing
pushable
is an indication that the pivot angle is right, but it seems, just that a
python is rideable does not ensure it is also pushable.
I do own two such specimens. Both of them ride quite nice and I do so in
public traffic.
For a python to be pushable, I think, beside having the pivot angle right
you need to be able to put sufficient weight on the pivot while pushing. If
the back of the seat is to far back, you may not be able to.
Gerald
On 17.3.11 5:14 , Vi Vuong wrote:
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 recently came back online, so I was able to
>download the program to play with. It must be a newer
>versionbecause 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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