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How Light Can They Get?

With the introduction of Honda’s CBR929RR (379 pounds dry) and Suzuki’s new GSXR750 (365 pounds dry) I began wondering just how light sportbikes can be made with current materials science.

The current formula seems to include aluminum beam frames and swingarms, with a sprinkling of magnesium among the engine covers, and titanium in the exhaust header, muffler or both. Somehow, manufacturers are finding a way to include exotic materials in their bikes without raising the prices. Pretty impressive, but how light can production sportbikes get?

I often think about motorcycle design, and I have investigated lightweight frame materials by looking at other disciplines (notably, bicycles). Bicycle frame technology is interesting, primarily because the combination of light weight and strength in bicycle frames is even more important than in motorcycle design. There are production, off-the-shelf bicycles with titanium frames, carbon fiber frames, and all sorts of exotic alloys (ever heard of Scandium?) With the major sportbike manufacturers doing their best to reduce weights in an expensive game of one upmanship, you can expect to see more of these materials in production motorcycles in the years to come.

In thinking about other techniques for reducing weight, it dawned on me that the ultimate technique would be to reduce the number of cylinders to one. We’ve talked about this before at MD, and our readers seem to have a passion for lightweight, single cylinder streetbikes. Will the manufacturers begin to produce lightweight street singles? We think so, and we think this could be a new growth market.

You always need one manufacturer to lead the way however, and light weight street singles are probably viewed as a risky niche. Nevertheless, we think they will be built, if only for one reason. Yamaha’s YZ400 motocross bike has directed a large amount of money and engineering towards development of light and powerful single cylinder, four-stroke motors. With the motors already developed, one or more manufacturers will “take the plunge” and build a street single. You can bet we will be the first ones in line to ride one when they do.