FEATURE THE FRAME GAME
Amotorbike chassis is just some metal that's been formed and welded to hold everything the motorbike needs in place, like the engine, suspension, fuel tank and rider, to name just a few things, right? Well, sort of, except that its design, the material used, and how it is constructed is critical to how a motorbike feels and gives confidence to the rider. Get the sums wrong on a bike chassis and it doesn't matter how posh the suspension or tyres are, or good the rider is, the bike will be a hound. Just ask Honda how its MotoGP season went in 2023.
Walk into pretty much any motorcycle showroom and you'll see bikes with frames that have different approaches to the same goal. Steel tubes are the go-to solution for KTM on all of its frames and Ducati for most. Fabricated alloy is probably the most common material, and the construction technique for beam frames is used by pretty much everyone, and the Ducati Panigale and Monster use cast alloy ‘front frames’, which is essentially a way of connecting all the front suspension to the engine, effectively using the engine as the frame. There's a mixed bag of concepts and approaches to frame building, which suggests that there isn't a right or wrong method or material, which in turn suggests there are pros and cons for each concept. So, I took a trip to one of the best chassis builders in the business to ask some questions…
Harris Performance has been building motorcycle frames for the great and the good since 1972, with notable achievements along the way being its ‘Magnum’ frames during the 1980s, a particularly golden era which allowed manufacturers like Harris to take a powerful but bendy Japanese bike and make it much better by replacing the chassis with one of its own. In the 1990s, Harris was one of just two frame builders to be given the right to build frames for Grand Prix teams who could get their hands on a Yamaha YZR500cc V4 engine; the other was French manufacturer ROC. Indeed, Fast Bikes road tester at the time, Sean Emmett, raced a Harris-framed YZR500 in the 1994 500cc GP season.
In the early 2000s, Harris partnered with Suzuki to develop its GSX-R750 SRAD in World Superbikes and Honda with its SP-1 in British Superbikes, all the while still working behind the scenes on various projects in GP racing, including the Sauber MotoGP bike (which never saw the light of day) and the WCM MotoGP bike (which used a Yamaha four-stroke engine based on the R1’s). That bike competed in the 2003 and 2004 MotoGP Championship as Harris-WCM in the infancy of the four-stroke era. I could go on about Harris's
