A drive for change
When I was up at the National Motorcycle Museum, someone asked why the 1907 Peugeot-norton had a pedal chain but belt rear drive; if they had chains in 1907, why not use them instead of a slip-prone belt? The straightforward answer is that in the days of direct drive, engine to rear wheel, the shock of each engine stroke was absorbed by a belt, whereas a chain created unpleasant (and damaging) snatch. This persisted even into the gearbox era with ‘chain-cum-belt’, where the engine-gearbox drive was by chain, but with belt drive to the wheel. It took the invention of a crankshaft shock absorber, such as Triumph’s 1920 Model SD (‘Spring Drive’), to make chains acceptable. But I don’t think that’s the whole story. Manufacturers have often dabbled in new technology at their peril. In the 1900s, most people weren’t far off the horse-drawn era and belt drive was familiar; from agriculture to industry, belts flapped around pulleys powering machinery, making them a trusted source of transmission. By contrast, chains were frightening, thrashing about like a Bezerker’s flail over viciously sharp-toothed sprockets. Consider the massive gear reduction needed on a single-speed bike between engine and rear wheel; the rear sprocket would need to be so big you’d feel like you were riding a circular saw! Of course, Kawasaki in particular brought belt drive back in the 1980s – now with teeth – and once again claimed smoother power delivery and lower maintenance. Thinking about it, that echoes something else you notice walking around the National Motorcycle Museum – there aren’t many new ideas around now that haven’t been tried a long time ago.