The latest 500-class test tires from Dunlop are reputed to feel, initially, like a set of loose swing-arm bushings; as the bike is set into the corner, there is a rush of lateral motion as the considerable flexibility of the tire's carcass is taken up. Thereafter, it feels like the tire is against a berm. It is firmly planted, and grips solidly.
This is reminiscent of what riders had to say about the earliest Dunlop radials (1985) -- that they were, in feel, like loose bushings. Very quickly thereafter, the makers all settled upon low sidewalls and high stiffness. In 1989, Dunlop tested taller sidewalls. The growing lateral stiffness of chassis was progressively reducing bikes' ability to cope with small bumps -- and it's easier to make a new tire than a new bike.
Now it's happening again, only this time, the new tires are much more flexible -- enough so that at least one rider likens their feel to loose bushings.
It's natural for someone with both F1 and GP motorcycle experience -- former Dunlop race tire designer Peter Ingley -- to be attracted to the single-mindedness of F1 tire design, in which camber (inclination of the tire's plane out of the vertical) is virtually banished, and in which suspension remains always perpendicular to bumps. Mr. Ingley suggested to me in Australia this spring that suspension should do suspension, and tires should at all costs stick to their business -- grip. Maybe this simply cannot be -- at least at this stage of the motorcycle's development.
Perhaps in three years or so we may see prototype machines with either of two possible features;
(1) two independent suspension systems, one for vertical operation, one for in-corner duty at high camber angles. It would be easy to engineer sideways suspension with very limited travel, but there will be weight and complexity, as well as stability issues. Putting this sideways suspension into the tires is attractive because tires are already, to a degree, self-damping.
(2) a single suspension system as before, but which remains in its action always perpendicular to the road surface. There has been public chatter about Honda patents in this direction, and Hurley Wilvert (both a fine rider and clever engineer) proposed this as early as 1972-74