Abstract Motorcycles

When form departs from function

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Technical Editor Kevin Cameron shares his wealth of motorcycle knowledge, experiences, insights, history, and much more.Cycle World

When, one fine day in 1976, we took our two KR-750 roadracers to beautiful New England Dragway, Dave Peters was able to make 10-second runs on them. Performance was poor because we really needed some combination of lowering, wheelie bars, and a less-sensitive clutch to get close to the machines’ true capability.

Which is to say we should have spent the entry fees on lunch; a roadrace motorcycle at the drags is a non-functional abstraction. The high engine position necessary for corner clearance on a road course is an invitation to time-wasting wheelies at the drags. The 55-inch wheelbase so essential to quick turning in roadracing becomes a joke at the strip, where 70 inches would have been more like it.

The phrase that describes the situation is the old "horses for courses." Each type of riding calls for a different type of motorcycle. And, when you get down to details, even within a single kind of riding you may need more than one kind of bike. Former Suzuki roadrace tech manager Stu Shenton noted that you need four distinct motorcycles to get through a corner;

  1. A braking motorcycle, which transfers weight to the front tire promptly but carries its weight far enough to the rear that it doesn't "stoppie" prematurely. This bike also needs very stable steer geometry to prevent braking instability.
  2. A turn-in motorcycle, which needs quick steering of a kind that may be vulnerable to instability as braking trails off and the bike is rolled into the turning attitude.
  3. A turning motorcycle whose front and rear grip—whether on new or used tires—remain in balance and at high level.
  4. An accelerating motorcycle, which means engine and rider weight must be strongly biased to the front, to keep acceleration from being limited by wheelies. Pretty much the opposite of the first one above.

The constructor finds a workable compromise and the rider, by moving his or her weight around on the machine, tries to approximate the four characteristics as required.

Lately, motorcycle styling is being described more in wine-taster terms such as “scrambler, with a whiff of tracker." This refers to appearance only and not to the actual design features required in the specializations referred to. This is perfectly okay as long as riders don’t confuse form with function. Actual “scramblers” date to the era before Edison Dye popularized European-style motocross in the US.

Back in the early/mid-1960s, quite large bikes such as 650 Triumphs (considered large then, anyway!) were regularly run in “scrambles” events (compact dirt road courses, with right and left turns of various radii, and perhaps a jump). Scramblers took the form of lightweight off-road builds with dirt tires, high pipes, and nothing extra. In our own era it has come to mean restyling a midrange twin of some heft as a dirt bike. “Whiff of tracker” doesn’t mean no left footpeg and a wheelbase as short as an XR750; it means only a slight doff of the hat in that direction, such as routing both pipes high on the left side.

We have just emerged from an era in which function did interest buyers intensely—people waited for the hot new sportbike to hit the showrooms and Miguel DuHamel was the human face of Honda’s “CBR World.” Other specialized motorcycle forms also existed: sport-tour, adventure, cruiser, etc.

We are entering an era of experimentation in form. In the past, novelties such as Yamaha’s forkless what-is-it (1993 GTS1000) or Honda’s "Rune" and "Pacific Coast" were pushed to the back of the showroom and later quietly donated to the local tech school. Today the novelties may have a better chance. I certainly hope so!

As motorcycles take on more identity as art, function may become less interesting, and it is certainly refreshing to break away from rigid and unchanging categories. While the manufacturers must maintain their standards for safety, handling, and stability, the creations of custom builders may or may not be adequately functional. Is it reasonable to require that artists also be engineers? Maybe not, but then I imagine "custom airplanes" that for any number of reasons are incapable of controlled flight. If it cannot fly, is it still an airplane? My tiresome, picky brain proposes the parallel question regarding visually interesting and imaginative "motorcycles" that are functionally compromised or even completely abstract. I can see that I need to lighten up. There's an exhibit of knitted art (they're not sweaters!) coming to that little museum near Concord. I'll go to it and practice being more open-minded.