Greg Locock wrote:
Basically, if you had to design a tire for maximum grip, would you try and hold the contact patch square to the road, or would you roll it around all over the place? If you want to go fast round corners, do you want 3g of downforce, or 0.5g
The trouble with downforce on a bike is that ifit is symmetrical on the bike then it is acting like extra mass, that is it is on the same vector as the mass*acceleration, so although it helps to push the tire down onto the road, it also increases the outward thrust at the CP. Net result is bad not good once you exceed say 45 degrees of lean.
Now you could do something clever to make the downforce push down more than out in a corner, but I don't think that's happened yet.
isn't the effect of aero 'downforce' on cornering actually neutral ?
broadly, the lean angle from the vertical is the inverse tangent of the tyre's coefficient of friction
eg at a representative 61 deg lean and a corresponding Mu of 1.8
because a unit of the geometrically down component of the aero 'downforce' boosts cornering force by 1.8 units
while the associated geometrically centrifugal component of aero 'downforce' is also a 1.8 unit vector
(similarly the effect of aero 'lift' is also cornering neutral)
ignoring practical factors like rider body lean, bike attitude effects on AoA, and front:rear distribution of aero forces
body lean actually produces gains in cornering from downforce (and losses if there was lift)
if we had a V wing (like a Beech Bonanza tail) producing 'downforce' a rider could gain more (if using 'oversteer'/powerslide)
because the inner wing would be producing useful force geometrically down (and amplified for cornering by Mu)
and the outer wing (if held at a low or zero AoA by the oversteer angle) would be producing little force anyway
'oversteer' by its effect on whole-body AoA has with current machines some benefits by producing favourable whole-body force
(ie both geometrically downwards and centripetal components)
given also the huge geometrical conflicts in the (cornering) contact patch, 'point and squirt' riding makes ever more sense