Yellow Bicycle Demos

    

An old banged up yellow bike that  Andy found some place has proved to work out well for bicycle stability demonstrations. Its forks have got a bit bent from smashing into curbs, but if anything that enhances its self stability.

Here are some photos of it riding self-stably:

	Photo 1: Saskyalaunch3517.JPG (709KB) Launching the yellow bicycle.
	Photo 2: InMotion3490.JPG (886KB) Yellow bicycle in motion.

Here are some videos:

(All videos have a large size HD version and a small size web version)

	Video 1: Long straight stable run. large size   HD: longstraightsideviewsmooth36b.mov (91MB) small size web: longstraightsideviewsmoothsmall36.mov (1.7MB) or on Youtube. The bicycle is launched and then balances by itself until it gets too slow.
	Video 2: Perturbed stable run. large size   HD: Perturb21b.mov(59MB) small size web:  Perturbsmall21.mov(1.0MB) or on Youtube. After launch the bicycle is knocked sideways. It then recovers and continues going straight.
	Video 3: Perturbed stable run, in slow motion. large size   HD: PerturbSlomob.mov(11.5MB) small size web:  PerturbSlomosmall.mov(1.6MB) or on Youtube. After the perturbation, in slow motion you can see the bicycle self correcting. When it leans right it steers right to correct. When it leans left it steers left to correct.
	Video 4: Locked up steering, unstable. large size   HD: stringtie53b.mov(120MB) small size web: stringtiesmall53.mov(2.0MB) or on Youtube. Automatic self-stability depends both on leaning and on steering. If you tie up (lock up) the steering the bicycle falls when it is moving just as fast as it falls when it is not moving. Free up the steering and the bicycle can self balance.
	Video 5: Rolling backwards, unstable. large size   HD: backwardsunstable80b.mov(89MB) small size web:  backwardsunstablesmall80.mov(1.2MB) or on Youtube. A rolling hoop is stable rolling frontwards and backwards. An early theory of bicycle stability was that it was like a rolling hoop. Lets see how stable a bicycle is rolling backwards!!!

Links:

Two-mass-skate (TMS) bicycle, stable without gyros or trail (available in two places):
http://bicycle.tudelft.nl/stablebicycle/
http://ruina.tam.cornell.edu/research/topics/bicycle_mechanics/stablebicycle/

Andy Ruina's Bicycle Mechanics and Dynamics webpage:
http://ruina.tam.cornell.edu/research/topics/bicycle_mechanics/overview.php

Arend L. Schwab's Bicycle Mechanics and Dynamics:
http://bicycle.tudelft.nl/schwab/Bicycle/index.htm

- Any questions or comments? Please contact Arend L. Schwab -