We’ve peered back in time to the early days of the universe, just following the massive Bang, and unraveled the mysteries of the human genome — yet we don’t really know the way a moving bicycle manages to remain upright with out a meatbag manning the handlebars. Scientists have long thought that it had something to do with the gyroscopic effect created by the spinning wheels and the caster effect of getting front wheel trail the steering axis (don’t worry, it’s all explained in a video on the source link). Researchers at Cornell, however, have created a tiny bike that generates neither of these effects yet, because of carefully calibrated mass distribution, still stays vertical when moving over 5MPH. The insights learned here could lead on to self-stabilizing rides for us and cooler wheels for our pedal-happy automatons to inherit. PR after the break.
ITHACA, N.Y. – In a discovery that can bring about better and safer bicycle design, researchers have shown that long-accepted “gyro” and “caster” effects aren’t had to make a motorcycle balance itself. The truth is, it’s a mix of complicated physical effects – associated with the distribution of mass – that makes it so a bicycle can remain up when moving.
This finding was demonstrated on a riderless bike by researchers at Cornell University, the University of Wisconsin-Stout and Delft, The Netherlands. (Science, April 15, 2011.)
“It’s all about how bicycle leaning automatically causes steering, which could bring the wheels back under a falling bike,” said Andy Ruina, professor of mechanics at Cornell and a co-author at the paper titled, “Bicycles may be self-stable without gyroscopic or caster effects.”
The path or caster effect is named that since the front wheel of a motorcycle behaves just like the front caster wheel of a grocery cart.
To prove that gyro and caster effects weren’t needed, the researchers built a riderless bicycle with two small wheels, each matched with a counter-rotating disk to eliminate the gyro effects, and with front wheel contact point slightly prior to the steering axis, giving it a negative caster effect. When launched at greater than about 5 mph, the research bike – like many bicycles – still balanced itself. In case you knock it slightly to 1 side, it straightens itself back upright.
“We have now found that just about any self-stable bicycle will be made unstable by misadjusting either the path, front-wheel gyro or front-assembly, center-of-mass position,” the researchers explained of their paper. “Conversely, many unstable bicycles could be made stable by appropriately adjusting any individual of those three design variables.”
While their work was intended to achieve insight into the character of bicycle balance, the researchers said, their analysis might result in further improvements in bicycle design.
“The evolutionary process that has ended in common present bicycle designs would possibly not yet have explored potentially useful regions in design space,” the report concludes.
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