[python] Re: Bipolar update
- From: Vi Vuong <vi_vuong@xxxxxxxxx>
- To: "python@xxxxxxxxxxxxx" <python@xxxxxxxxxxxxx>
- Date: Mon, 11 Jul 2011 00:17:36 -0700 (PDT)
if the rear pivot points forward, the rear wheel probably would counter steer
and makes the bike unride-able at 60 deg. As is, I can park the bike with the
wheels turned in opposite direction to make it look uninviting :)
Looking at the second video from an observer point of view, the bike does
meander more like the real animal. http://www.youtube.com/watch?v=abNt5v9CsHg
Maybe it's time for a python skin shell (costume)...
>________________________________
>From: Olaf Johansson <noll@xxxxxxxxx>
>To: "python@xxxxxxxxxxxxx" <python@xxxxxxxxxxxxx>
>Sent: Sunday, July 10, 2011 1:11 PM
>Subject: [python] Re: Bipolar update
>
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>Nice! What would happen if you changed the design so that the rear wheel is
>countersteering? That would perhaps make turning radius even shorter? Maybe it
>would make it impossible to ride straight? Making it unrideable. And
>theft-proof.
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>Olaf
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>10 jul 2011 kl. 21:26 skrev Vi Vuong <vi_vuong@xxxxxxxxx>:
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>Riding hands-free is great, especially when the scenery is nice. Best
>comments I got from the trip are:
>>
>>
>>That't not fair - from someone riding roller blades
>>He's lying on a bike - from a kid
>>Can we make that bike? from another kid
>>...
>>
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>>http://www.youtube.com/watch?v=abNt5v9CsHg
>>
>>
>>
>>>________________________________
>>>From: Vi Vuong <vi_vuong@xxxxxxxxx>
>>>To: Python <python@xxxxxxxxxxxxx>
>>>Sent: Saturday, July 9, 2011 9:30 PM
>>>Subject: [python] Bipolar update
>>>
>>>
>>>
>>>
>>>When disassembled, it managed to fit inside a medium luggage (largest that I
>>>have), where the micro python would need another inch or so. Thus it got to
>>>go traveling first. Fortunately, the total weight is under 50lbs, so no
>>>extra luggage charge ($100?).
>>>
>>>
>>>Climbing is rather poor, as front weight distribution is ~40%. Walking is
>>>tough, and barely with a stick at the front. Carrying the 25lb folded bike
>>>uphill is no fun either, so a upright folding bike is better here,
>>>especially in the city...
>>>
>>>
>>>Downhill is not too scary anymore with some braking. I can go faster than
>>>going uphill now :) On the flat, I am comfortable enough to share trail /
>>>pathway with pedestrians now (when legal).
>>>
>>>
>>>The 2-piece seat is marginal so I had to pick up a mesh back support on the
>>>trip, not bad for
>>>$1, http://www.google.com/search?q=back+support+mesh&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&hl=en&tab=wi&biw=1440&bih=814.
>>> A hotel towel would also helps. Because the seat rest is coupled to the
>>>rear wheel, starting is a little tougher even with sticks, and care is
>>>required to ensure that the back seat / rear wheel is straight.
>>>
>>>
>>>Luckily, while experimenting with uncontrolled rear wheel, I found that the
>>>bike is actually more compliant. The rear wheel is now mostly free from the
>>>seat back, other than some pressure / friction, and straightens out nicely
>>>under weight, and seems to move slightly with the front wheel due to the
>>>pendulum effect, and probably vice versa (another invisible link like the
>>>bango steering http://www.youtube.com/watch?v=jzUr3GI_ulE).
>>>
>>>
>>>There also seems to be some sort of self-stabilizing effect (PSI reduction?)
>>>between the two wheels that deserves more analysis, beyond quick all-wheel
>>>steering. Since the camera is mounted to the rear frame, so it's not very
>>>obvious that the rear wheel rotates unless you pay attention to the view
>>>through the wheel. http://www.youtube.com/watch?v=vswF-qqcwg0 ; See the PSI
>>>test at 1:06-1:15. The bike feels quite stable as going straight. I will
>>>repeat the test on regular pythons...
>>>
>>>
>>>Vi
>>>
>>>
>>>
>>>
>>>
>>>
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