What makes a motorbike go round corners?

[stinkwheel]

Serious question, I have silly ideas from time-to-time and it occurred to me that I'm not really sure.

Not asking how you initiate a turn, what actually makes it go round the corner once it is leaned over and not just carry on in a straight line while leaning over.

Is it the weight of the rider in relation to the bikes centre of balance? The angle of the wheels in relation to one another? The differing angles of gyroscopic force in the wheels? The angle of the tyre contact patch in relation to the angle of the road surface?
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[Fisty]

All of the above.



And magic.
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[Pickledswede]

Isn't it because due to the profile of the tyre, when it's leaned over the corner side of the contact patch has a smaller circumference than the furthest away bit, meaning it travels less far for every one turn of the wheel?

-Edit- Reading this back it seems a bit confusing.

When a tyre is travelling standing straight up, every ring around the tyre within the contact patch (so for example a millimetre width of tyre the entire way around the circumference) is the same length. However when you lean it over a different patch is in contact, on the side nearest the centre of the tyre the ring around the tyre is one length, and due to the shape of the tyre, the ring furthest from the centre (and on the side of the corner) is shorter, all the rings in between will be different lengths from large to small. The longer circumference near the centre of the tyre means one turn of the tyre is further on the ground than it is on the other side of the contact patch.

[Scythe]

https://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics
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[Howling TerrorOutOfOffice]

No cheating here even tho i have read about it.

You need momentum to corner. Once in a leant state it is gravity, centrifugal force and the amount of that momentum will affect how it goes around the corner.

[MarJay]

They kind of explain it in the "A twist of the wrist 2" DVD.

[Andy_Pagin]

Okaay.. Either grab yourself a degree in mechanical engineering (or at least 'A' levels in physics & pure & applied maths) and it will all become clear (probably ),

or...

like the rest of us thickos, just accept it's 'magic'
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[stinkwheel]

[flat spot]

Here's a practical thing to do. Hold a push bike wheel by its axles and get it spinning. A big wheel off a racer is best. When you lean the wheel over forces actually turn the wheel in your hand (right or left) the way it you would want to corner if you lean that way on a bike.
It's sort of difficult to explain, but if you do it all will become clear. It's also quite entertaining for a while.

[ajbsmirnoff]

stupid wine induced double posting

[ajbsmirnoff]

[Tristan.]

Read John Robinsons "Motorcycle Tuning: Chassis" explains it very well in the first chapter. In short it's a combination of the radial thrust due to the profile and position of the tyres (similar to what pickledswede said) balanced with the weight distribution body position etc.

[Cheeseybeaner]

[binge]

When a wheel is upright, the "leading edge" of the tyre falls directly in front of the current contact patch on the road.

When a wheel is lent over, the leading edge of the tyre is now off center to the "center line" of the bike.




Ben

[Killer Rat]

on the way home tonight i was pondering stinky's question and have noticed that on some bends with my bike (cbf125) if i take a sharp bend in 2nd at 30mph i can keep the bike on the tyre line, however, the same bend at the same speed but in 3rd gear i find the bike veering into the oncoming lane.
I was wondering if revolutions come into play when holding a line.
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[binge]

[Killer Rat]

[binge]

[Howling TerrorOutOfOffice]

OT. Know one thing. A bike that's set for the rider doesn't half feel nice in a corner Finally got round to tailor the duc to my weight..Life is good.

[Skudd]

[Kickstart]

Hi

My understanding is that it is the shape of the tyre that causes the bike to gor round a circle. Like a cone rolling on its side.

Leaning over more just means steeper angle of the cone and the tighter the circle. But that needs to be counterbalanced with the centrapedal force pushing the bike to lean in the opposite direction and gyroscopic forces leaning it over.

All the best

Keith
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[Howling TerrorOutOfOffice]

^^^@Skudd. Nowt probably...

Thank fuck keith turned up.
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[Kickstart]

[Skudd]

[karoshi]