Disc Brakes
Motorcycle disc brakes were a genuine innovation, and like so many other ideas, originated in the dim past. But as drum brakes were becoming marginal in the 1950s and 1960s, particularly for racing, innovators like Grand Prix racer Peter Williams began to seek fade-free performance from automotive disc brakes of the period. Honda put a single front disc brake on its 750cc Four in 1969, and by 1972, discs were the new standard.
Slipper Clutch
As you brake hard and downshift when aggressively entering a corner on a large-displacement four-stroke, the drag of engine braking tends to make the rear tire hop or slide out to the side. MV Agusta, in its last racebikes of the mid-1970s, did not find a solution for this, and Honda encountered the same problem with its oval-piston NR500 of 1977-81. Honda, however, developed a device that partially disengaged the clutch when the rear wheel was driving the engine. This was the “slipper clutch,” now found on many sportbikes.
The Future
Motorcycles continue to have serious problems that cry out for innovative solution. To go around corners at today’s high angles of lean, bikes have to locate their engines and riders high enough to avoid dragging crankcase or footpegs on the pavement. But with major masses located so high, wheelies and stoppies occur at lower rates of acceleration/braking. Compromise!
Motorcycles are small, but their aerodynamic drag is relatively high because their short length allows no room in which to “close” airflow smoothly and with low loss behind the vehicle. A motorcycle’s wake therefore is turbulent and drag relatively high. Low-drag, fish-like shapes like those proposed by Craig Vetter or used on large “cabin bikes” just look weird to many riders. More compromise!
Yet another unsolved problem, most notably on roadracing motorcycles, is the behavior of suspension in corners. Conventional suspension works well when the vehicle is fully upright or only at moderate lean angles; but when at high lean angle in mid-corner, the suspension is mostly pointed sideways, making it almost useless if the pavement is not glass-smooth. At present, designed-in frame flex acts as a crude “sideways suspension” in corners, but it’s a tricky technique to make work right.
Obviously, there is a lot more to do! Anyone have an innovation to offer?
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