The fat part of the tyre. What?

[Cosmik de Bris]

In a lot of these videos and articles on cornering the advice is to get the bike on the fat part of the tyre to drive out of the corner. I presume the phrase "fat part of the tyre" to be purely idiomatic because as far as I can see the fat part of the tyre depends on the shape of the tyre. It is easy enough to make a tyre whose contact patch is equal at any angle of lean or even make the tyre fatter when leaned over than when vertical. It looks to me, on my bike, that the leaned over contact patch is bigger than when straight up.

It is true that the vertical force (weight) on the tyre is less when leaned over therefore reducing grip but it is not the fatness of the tyre that is reducing the grip. The tyre manufacturer could always compensate for this by making the contact patch larger at lean (if contact patch is really related to grip).

So, what's the real story?

Cheers

[Scubbo]

go have a read through this --- https://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics -- specifically roll velocity and the parts before explaining how tires work / steer

[pritch]

Don't get too technical at this point it may just confuse.

Profiles vary but what they are suggesting about the fat part of the tyre is to get the bike vertical as soon as possible when exiting a corner. That is summed up in Simon Crafar's MotoVudu as follows:

"Make the straights as long as possible and the corners as short as possible"
"It's not who gets on the gas first, it is who gets on full gas first."

And for that the bike needs to be upright. There's more detail but that's the guts of it.

[george formby]

Yup. I watched a vid of a UK car journalist trying to achieve a similar lap time on an S1000RR BMW, that he managed in a supercharged Merc, the one that's mainly bonnet with the funny doors.

He had been riding 6 months and was attending the California Superbike school, he was a muppet on a bike, muppet in a car, too.

Frequently mentioned was getting the bike upright to attain the grip necessary for maximum accelerato in the direction one would like to travel.

Shame he didn't give the bike to an instructor for a comparison.

I should imagine the contact area of the centre of the rear tyre increases quite a bit under accelerato unlike the sides.

[AllanB]

If it ain't slipping, keep tipping.