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Every bit of advice you get on a mountain bike tells you to lean the bike not your body into a corner, steer with your hips, weight the outside pedal and possibly even press your outside knee against the frame all in order to get as much weight as possible over the area of the tyre contacting the ground in a corner.
On a motorbike, you are taught that bike lean angle should be as low as possible whilst compensating with a body leant out over the bike. Ie. the opposite.
Surely the mechanics are largely the same, give or take speed and surface grip.
Could anyone explain this to me a bit better?
On a motorbike you weigh less than the bike, on a Mountian Bike it’s rhe other way around.
Weight, how much difference in weight is there
It's not just the static weight of the bike and rider but the weight transfer that has a huge effect on grip. Body position will change a bicycle's handling more than a motorbike's.
A motorbike is also likely to be going faster round a corner, meaning greater force trying to push the bike upright which the rider needs to counteract.
For a given speed and corner radius, the angle between the contact patch at the centre of mass of the rider + bike will be the same. You can reduce the lean angle of the bike by the rider leaning in more and vice versa.
On a mountain bike, leaning the bike more gets it on the knobbles on the side of the tyre for more grip. On road, on a motorbike, leaning the bike less means you can go faster before the bike grounds out.
What people tell you because it's easy to visualise isn't necessarily the same as how the physics actually works. The vertical weight on the tyres is the same, however you lean, because the mass is the same and gravity is the same. Similarly, you are trying to make the same mass turn, ie, accelerate it in a different direction, and that requires the same horizontal force. So with the same horizontal force and the same vertical force, the combined CofG of bike and rider has to lean to the same angle. What you [u]can[/u] change is the relative lean of each, and (as in posts above) that enables you to get the right amount of lean more effectively - it also affects which part of the tyre is in contact. Also you can change the distribution between front and back wheels, the consistency of the lateral force (ie, turn radius), both of which can affect grip. There are also things you can change by dynamics, ie, moving (not positioning) your CoG relative to the bike, to temporarily weight or unweight the contact points.
On the road you have a lot of grip and it's consistent, off road it the opposite. MX bikes corner more like mountainbikes.
The point of leaning the bike over means that if/when it slips it moves up towards you and get's corrected automatically. If you watch a motorbike crash they tend to do what's called a 'high side', which is where the bike slides, regains grip then catapults the rider over the top. If you rode them like you do an off-road bike that wouldn't happen, but you'd also be slower because the lean angle is less.
Are you talking road or off-road motorbike? Cornering a road bike you keep your weight over the centre of the bike, none of this leaning the bike more stuff.
When I used to race my Enduro Motorcycle off-road I would ride it like I do my mountain bike.
Lean the bugger over, the knobblies would still stick into the ground and I would be fine cranked right over. Look at an off-road motorcycles tyres, they are the same profile as mountain bike tyres.
Whereas on my road bike they are not, so Id lean off the bike and stick my knee on the ground. If not Id end up grinding the foot pegs into the road.
Its a lot to do with tyre width. Modern motorcycles have wide tyres so the contact patch moves 3 inches or more off the centre line. The hang off is to put the centre of gravity back in the right place. Old school narrow tyre motorbikes are better ridden in line with the bike - no hang off or even like a MTB - push the bike down into the corner
Hanging off a modern sports bike also reduce the lean angle for a given cornering speed so gives great ground clearance. Of course this only matters if racing but is copied by road riders.
Check out pictures of Geoff Duke - never hung off a bike in his life