johns (05/12/83)
Could someone explain the physics of how it is possible to ride a bicycle with no hands?
dkw@brunix.UUCP (05/25/83)
I'm afraid that I am not convinced that the gyroscopic effects are the only
reason a bike stays upright. There are two arguments against this:
1. If it is a gyroscopic effect anyone should be able to stay on a bike and
training wheels should be of no help to anyone trying to learn how to
ride. I have seen beginners who have trouble with balance, so
presumably there is some skill involved in balancing.
2. How do I manage not to fall when ice skating? My center of gravity is
almost as high, the speeds involved are comparable and there is no
gyroscopic effect. Skill at bicycling appears to carry over to
skating ( at least the ability to balance when one starts), so it seems
likely that similar affects are involved.
David Wittenberg Brown University
{decvax, yale-comix, cornell, ihnp4, vax135, allegra}!brunix!dkw
dkw.brown@udel-relay (csnet)moore@ucbcad.UUCP (05/26/83)
#R:utcsrgv:-138300:ucbcad:10400001:000:472 ucbcad!moore May 26 00:00:00 1983 One of the tests made was to attach a counter rotating wheel to the bike, geared so that it had exactly the opposite angular momenta as the two main wheels. This did NOT affect the stability of the bike. So gyroscopic stability is not the important factor in bike riding. The balance must be a dynamic effect. The trouble with physics and real life examples is that the obvious, neat explainations hardly ever work. Peter Moore moore@Berkeley ..!ucbvax!moore
jlg@lanl-a.UUCP (05/28/83)
Relay-Version:version B 2.10 5/3/83; site mhuxt.UUCP Message-ID:<327@lanl-a.UUCP> Date:Fri, 27-May-83 17:24:27 EDT I can pedal my bike no handed!! No balance problems at all.
mason@utcsrgv.UUCP (Dave Mason) (05/30/83)
I'm no physicist, BUT...someone suggested that someone else had tested the idea of gyroscopic effects helping cyclists by building a bicycle with "wheels geared to have the opposite angular momentum..." SO WHAT? adding more spinning wheels seems to me to increase the gyro effect. I was going to stay out of this discussion, but the above rankled too much...(almost like bubbles making ice float)...so now that I've started... I think that there is a substantial assistance provided by the gyro effect a) if you take a dismounted, spinning bicycle wheel and attempt to turn it there is a substantial resistance. b) when people are learning to ride they typically move VERY slowly, and are constantly making extreme corrective motions that would easily over- whelm the gyro. If you send even a novice fast down a hill, they will usually stay upright until they panic or slow down. c) all of which is not to say that I think balance is un-important. ....flames, etc welcome..../Dave (...decvax!utzoo!utcsrgv!mason)
mmt@dciem.UUCP (Martin Taylor) (05/31/83)
The whole question of bicycle physics was dealt with in a Scientific American article (I think it was a cover article) a few years ago. Gyroscopic action has nothing to do with it, but the placement of the front hub with respect to the projection of the shaft which connects the handlebars to the front wheel is the key factor. A bike can be made so stable that it is tough to shift from its chosen path, or so sensitive that it needs continuous monitoring. I don't know the details, but you could find the reference in an index to Scientific American.
trb@floyd.UUCP (06/02/83)
When I was about 13, I tried (exactly twice) to ride my bicycle gripping the handlebars with my arms crossed in front of my body. I lost control and fell off immediately on both occasions. I guess my instinctive muscle movements overrode the natural stability of the bike's design. Andy Tannenbaum Bell Labs Whippany, NJ (201) 386-6491