Asterix,
I wanted to address this as it is a common misconception.
How could accelerating "push" the front contact patch. Is there more or less weight on that front contact patch when you're accelerating? If you say less, why would that put more force on it to cause a steering input that brings the bike upright?
The bottom line is that accelerating will not change your lean angle, only a steering input will. Keith addresses this in his book but I don't have it handy to give you the chapter number, but as I recall it is called "Steer With the Rear" or something along those lines. However, going faster with the same lean angle will affect your line. So the question to you is: how will that affect your line... will it be tighter or wider as a result? Could going wider be perceived as the bike "coming up" out of the corner?
Benny
Well, when you accelerate, the rear wheel is pushing the bike forward. If you are also turning, your front wheel is pointed in some direction that isn't completely inline with the rear wheel, thus, the force being generated by the rear wheel is different from the front wheel's rotation. From what I can tell, this means that the front wheel will be rotating, say 5ยบ to the left of the direction that the rear wheel is rotating, and there will be a shear force from the ground pushing against the front contact patch (inline with the rear wheel) which will be trying to push the front wheel back inline with the rear wheel---basically the same thing that happens when you brake in a turn with the contact patch plowing (shown in the TotW II video). I understand that weight shifts back when you accelerate, but the contact patch is still touching the ground, so there's still some plowing---wouldn't that have the same sort of effect with acceleration?
I might be misunderstanding something with the physics here though. If lean angle doesn't change with acceleration, what am I missing/misunderstanding?
Regarding the same lean angle with more speed affecting your line, I agree that your line will have to widen so that the force of gravity and centrifugal force cancel out. But, how can your line widen without some sort of steering input? If the tires are at the same angle with the ground, and the front wheel has the same amount of "turn", and you are accelerating, the bike would end up out of balance and "fall" out of the turn (basically topple over to the outside), rather than widening its line, unless the tires start sliding.
It seems that my explanation above with the plowing would answer this; you accelerate, the plowing at the front wheel countersteers the bike up, decreasing lean angle, and widening the turn. To keep the same radius, you counter the plowing force (by countersteering), and increase lean angle, keeping the bike in an equilibrium state. No?