Drawing the Line - End of The Motorcycle Frame?

An intriguing U.S. patent application showed up at the Motorcyclist offices the other day, causing a stir. Why? The Ducati depicted in the drawings lacked the traditional trellis frame; in fact it didn't have a frame at all. Where have we seen this before? On the GP9 racebike, of course.

It's been difficult to ascertain much about the GP9 from photographs, and therefore the patent application reveals hidden details. Basically, the chassis is composed of three structures that bolt to the engine. The swing-arm pivots at the back of the engine cases, while the seat and footpegs bolt to the engine at the swingarm pivot and the back of the rear cylinder head.

The third structure is the most innovative. A complex box bolts to both front and rear cylinder heads and contains the steering head for a conventional fork. This box, bridging the V of the engine where the intake ports and throttle bodies mount, also forms the airbox.

Previous MotoGP Ducatis have used the same layout, but the front structure was an abbreviated trellis. In a sense the GP8 was the last of the trellis-framed MotoGP bikes, even though the trellis was much smaller than on Ducati's streetbikes. The box is an innovation in the use of materials and in the combination of structure with airbox.

That this development is now patent pending likely means Ducati intends to put it into production. The application describes the front box as being made from composites or light metal (aluminum or magnesium). Carbon-fiber would present production difficulties that aluminum won't, so the mention of metal for the box implies production intent.

A Ducati streetbike without some form of trellis frame may be hard for the Ducatisti to swallow. I've been told by insiders that Ducati will never give up the trellis, but one only has to look at the GP9 to see that one should never say never. In the accompanying digital illustration, based on the patent drawings, we can see the concept applied to a V-twin rather than the V4 of the GP9. The concept works much the same. There would have to be significant changes to the familiar Ducati "L-twin" to make the box workable on that engine, but it's more a matter of will and marketing than of technical difficulty.

Ducati will continue to test and evaluate the "frameless" concept on the new GP10 MotoGP bike. Will we see a prototype based on the World Superbike machines? I'd give it a better than 50/50 chance now that we've seen the patent application. The late John Britten showed a similar structure on his bikes in the early '90s (although the box in Britten's case held a Hossack suspension rather than a fork, and didn't contain the airbox). Britten's untimely death meant that we didn't see where the idea could go. With Ducati's impetus, we may see this idea fully developed on bikes we can buy.

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