Valentino Rossi, in his charming English-as-a-second-language sort of way, calls it the “slippery clutch”. A device he was forced to use when the highest form of motorcycle racing changed over to four-strokes two years ago.
A slipper clutch is now found on more than one production sport bike, and, as evidenced by our recent track test of the 2004 Kawasaki ZX-10R, is a tremendous aid to aggressive riding on the track.
It also makes for smoother riding on the street — something we learned testing an Aprilia Mille last year here in Southern California.
Considered a somewhat exotic device on a street bike just a year or so ago, the slipper clutch should quickly become standard on virtually any competitive production sport bike (either 600cc or 1000cc). Expect to see it take over the open-class, first.
Should you care? If you are a hard core sport bike fan, or a track day addict, absolutely. For other riders, it is a less important device, which could arguably lead to a generation of sloppy down-shifting by riders who are free from concern about wheel hop and other engine braking annoyances. In the meantime, remember to blip the throttle with each downshift.