My son is studying motorcycle engineering
And he reckons that just about every explanation of how bikes steer is wrong - I'll have to send him this to see if it's an exception. It certainly seems to cover topics that are often missed out, like the gyroscope effect.
He showed me the telemetry data from a MotoGP bike, and it was staggering how the steering position was essentially still round the whole track.
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tarka_dall Like normal dall, only a bit more spicy, Thu 11 May 2023, 17:59,
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I think the physics of motorbikes and bicycles differ quite a lot in some key areas....
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Happosai _,,,,_(O ; o)_,,,, Thu 11 May 2023, 19:34,
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Yes, on a motorcycle it's not steering so much as a controlled fall*.
*beyond walking pace.
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FeralCatMan Unusual disease collector., Thu 11 May 2023, 19:44,
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Aside from the obvious differences
Such as the effect on suspension from the chain tension and the lower centre of gravity on motorbikes, I'm not sure if there really are that many differences - particularly the physics of getting the bike into a turn and what keeps it stable during a turn are pretty much the same as far as I can see. When riding without hands, I find that steering a bicycle and motorbike are very similar other than bicycles requiring rather less effort.
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tarka_dall Like normal dall, only a bit more spicy, Thu 11 May 2023, 20:45,
Reply)
But most explanations about how bikes steer at speed would confirm that the steering position remains practically static.
I suspect that the effect would be greatly exaggerated on a Moto GP bike given the speeds the riders are traveling at, the amount they lean and the resulting forces acting on the bike, but it's precisely the same theory for a boring old pushbike, too.
The easiest way I've found to explain this in a practical sense is to do it in reverse. If you tip a stationary bike to the left, the front wheel steers to the right. If you tip it to the right, it steers to the left.
You always want to lean into a corner to maintain traction, so you want to tip the bike in that direction, but all it takes is a tiny nudge to initiate that lean. And once you're in the lean, it only takes a tiny amount of correction via steering to maintain and then exit it.
It feels very much like you're actively steering the bike by changing the direction of the front wheel at these speeds, but if you consciously tried to steer in that manner at anything over jogging pace, you'd go over the bars.
(, Thu 11 May 2023, 21:32, Reply)