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krab
krab is offline
#17
Aug9-04, 04:20 PM
Sci Advisor
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Quote Quote by Albert's your uncle
Just seen this post and it reminded me of an experiment where a bicycle was pushed down a slope without a rider (so no moving the handlebars to regain balance). Once the bicycle was pushed to a slow running speed, it was let go to run down the hill on its own. It accelerated at first due to the hill's slope and the bicycle carried on going until it reached a flat piece of ground and slowed down. It was only when it had slowed to a walking pace that the bicycle fell over.

So, the balance of a bicycle when being ridden is the same as a bicycle travelling at speed without a rider. This brings doubt to Krab's theory of moving the handlbars to get the "moving of your point of support". The bicycle somehow manages this on its own. So it must be more to do with the gyroscopic effect caused by the motion of the wheels.
That's strange, first you present data that is completely consistent with what I said in my post, then you say my post is wrong. Maybe you should read it again. "Bicycle manages stability on its own" when going fast enough; just as I said one can ride with no hands (I called it phase 3). Bicycle fell over when speed dropped below walking pace; just as I said (called it phase 2)

Quote Quote by Rogerio
The gyroscopic effect is the unique reason for the balance
You then cannot explain why it is possible to balance a bike at such a slow speed that gyro effects are negligible (what I called phase 2).

Quote Quote by G
As far as I know the bike turns because of camber thrust.
This is an interesting claim. How does it scale with tire width? I ride both a motorcycle and a bicycle, and the difference in tire width is larger than a factor of 4! Yet they steer pretty much the same, or IOW I've always attributed the difference to the difference in mass; mass of spinning tire and also moment of inertia about steering axis.