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From: levy@ttrdc.UUCP (Daniel R. Levy)
Newsgroups: net.cycle
Subject: Re: The Backwards Bike
Message-ID: <687@ttrdc.UUCP>
Date: Wed, 22-Jan-86 20:28:50 EST
Article-I.D.: ttrdc.687
Posted: Wed Jan 22 20:28:50 1986
Date-Received: Sat, 25-Jan-86 08:14:51 EST
References: <3007@vax4.fluke.UUCP> <756@athena.UUCP> <63@fai.UUCP> <577@amiga.amiga.UUCP>
Distribution: net
Organization: AT&T, Computer Systems Division, Skokie, IL
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In article <577@amiga.amiga.UUCP>, jimm@amiga.UUCP (Jim Mackraz) writes:
>I am sure I once read an article on some study being made to determine why
>bicycles are stable.  They tried everything, including teeny front
>wheel, backwards bend in the front fork (which was used to _increase_
>stability in early bicycle speed record runs (+100mph)), counter-rotating
>dummy front wheel, and so on.  None decreased the stability markedly (they
>could draw no conclusions on the teeny front wheel idea, since the caster
>they used would burn up).
>

Bicycles, motorcycles, unicycles stay up because the rotating wheels are
in effect gyroscopes.  They resist any attempt to push them directly
sideways.  I thought this was common knowledge....

>Not until they put the steering in the rear did they create an "unridable"
>bike.
>

This is indeed an unstable situation much like the modern fighter jets
which need constant computer control to keep them from breaking up almost
immediately.  In the case of the rear-steering bike, any steering away from a
dead straight course quickly magnifies itself till the bike is out of
control.

Now if the cycle steering could be computer controlled then the rear
steering might be a viable idea :-).

I cannot see why anyone WHO KNOWS PHYSICS AND CONTROL THEORY could envision
a stable, directly human controlled rear-steering two-wheeled cycle.  The
physics is just wrong for stable control.  I still can't lead myself to
believe this Joan whatsherface who proposed it had even a physics background,
and that nobody caught that fiasco of an experiment until it actually failed.
Any mechanical engineer could have caught it at once.
-- 
 -------------------------------    Disclaimer:  The views contained herein are
|       dan levy | yvel nad      |  my own and are not at all those of my em-
|         an engihacker @        |  ployer or the administrator of any computer
| at&t computer systems division |  upon which I may hack.
|        skokie, illinois        |
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