MOTOGP » Stoner keeps 'new set-up' on top

Jack,
I think the turn grip is causing confusion. If by grip you mean mu, then it does go down with vertical reaction but if by grip you mean friction force then it obviously goes up with vertical reaction.By the way I used to read a lot of Tony Foale'sarticles (but I haven't got hisbook unfortunately). He's one of the few people who talks sense about motorcycles (and that includes most "experts")

I meant term not turn!

Stoner is very fast,he can run away from Rossi

This topic has gone mad! Love teh whacked out physics. Lols

Yes he can shariff, but when they get on the motorcycles he has nowhere to hide...

eadgbe, I don't exactly know what you mean with "mu" but given that I certainly don't mean friction force I must be meaning this! Seriously though with "grip" I mean the centripetal acceleration, not force. This is where the misunderstanding lies.

Tony Foale's book is a revelation. I've been searching for a book like it for years. It conveniently answers questions that I've never ever seen anybody even close to answering. Did you know that grip is created from 2 different phenomena? Or why on slippery roads a fast flick of the bike causes the front end to slip momentarily?
Why the handlebars become "light" when close to the friction limit? This and many more are answered in depth.

Jack, eadgbe - please, guys, more of this good stuff, it's helping me sort out some things I thought I knew something about if only very superficially (I too have read some of the Foale stuff but he's over my head fairly quickly when the maths starts getting heavy, I generally have to skip to the 'plain English' conclusions but trust what he says totally). I understand the concept that the less mass you need to accelerate laterally the better (as a crude way of expressing it)for cornering but had thought that friction between two surfaces increases with contact force (up to a limit for the two interacting materials, I would guess)??

Yes Oscar you are right that friction increases with contact force, but contact force in bikes is created by its mass. However, the greater the mass the greater the lateral force you need to turn. So it is a question "which one increases faster"? In an ideal, mathematical world it is exactly the same, and mass becomes irrelevant, only the materials matter. However, the limitations posed by tyres and rubber and all this stuff means that in reality the lateral forces (friction) increase a bit slower than the vertical load. So, the lighter you are, the better.

Jack - thanks. Should I extrapolate from that that what we are doing in a long fast corner by modulating the throttle (short of actually spinning up the rear) is in fact balancing the grip levels between front and rear by variation of the effective mass on each wheel due to weight transfer?

Rossi's 8th championship... whoopee. I'd be more impressed if Michelin didn't suck so bad this year, or if they ran a spec tire.

I'd even be more impressed if he did it on Michelins like he ought to have.

For someone as talented as Rossi you'd think the thrill of winning championships without a significant challenge would've worn off by now.

When he switched from Honda to Yamaha and won... that was impressive. Now he's just riding for the record books... how exciting.