Sbarro Update: Tracking the Spokeless Wheel
Sbarro Update: Tracking the Spokeless Wheel
ROUNDUP
A WHEEL IS A WHEEL. ROUND, rimmed in black and supported by a few spokes, right? Well, not when Franco Sbarro gets his whimsical hands on one. Basically, as motorcycle wheels have developed, the number of spokes found in them has dropped from countless thin wires to a few alloy arms, but last year, Sbarro went even farther. He reduced the number to none.
This Italo-Swiss designer has come up with some wild flights of fancy before, but a rim with no spokes and no hub is pretty far out. You have to wonder if one of the eight patents Sbarro has registered in connection with this design covers thin air.
Sbarro’s theory goes like this: The only part of a wheel/tire combination actually doing useful work is the contact patch at the bottom. All other points around the rim are merely standing in line to reach the momentary work place, so why not eliminate them?
Key to his idea, which Sbarro calls the SM wheel, is a pair of thin, very strong rings the diameter of the wheeT rim. Barely half-an-inch wide, these have ball bearings between the inner and outer rings. All else, whether brake caliper or swingarm, flanges to these skinny rings. The brake disc is a ring itself, within the rim. Obviously, the only way to drive such an empty wheel is by chain (or belt) around its periphery.
Weight-saving virtues are readily apparent; possible drawbacks just as
evident. Gearing is dependent on the diameter of your rear wheel, or use of an intermediate stepdown box. And more directly, this question remains: Can mere ball bearings support the kind of side loads they’ll encounter in this use? First designs were delayed by the refusal of most major bearing firms to even try. Finally, SRO-FAG, a German manufacturer, made up a few sets.
Studying the layout, one wonders just how hot those bearings will run at autobahn speeds, not to mention how much they’ll be warmed by heat transfer from tire and brake.
When 1 first visited Sbarro at his shop northeast of Geneva last year, he had only just finished two SMwheeled bikes. Curiously, since then, though the bikes were runners and were given brief outings just to prove the idea really worked, Sbarro has concentrated on other projects. Ah, but that in no way means he's dropped the idea. He is, he says “working intensively with several firms” on his SM wheel, and intends to sign contracts any day. No, he wonvt say who he’s dealing with. He will say, however, that he doesn't forsee release of any additional information for, oh, maybe a year.
What can all this mean? Might just mean we’re dealing with a quirky, if brilliant, Swiss designer.
Or it might mean that in the not-toodistant future some manufacturer will build, for sale, a special motorcycle that uses spokeless wheels.
Which is it? Right now, that’s anybody’s guess. —Jerry Sloniger
