Ever since some car manufacturers proved that four-wheel-drive cars had the edge – in rallying at least – over their two-wheel-drive predecessors, people have wondered whether powering both the wheels on a motorcycle would be as significant step forward.
But now, 30 years after the car world was convinced by Audi, it's still virtually impossible to answer the question: Does two-wheel drive work on a motorcycle?
While you can go and buy a two-wheel-drive motorcycle – search for a Christini-converted motocrosser, or maybe one of the handful of Yamaha WR450F 2-Trac machines made five years ago – the chances are, you'll never get to ride one. That' a surprise, since virtually every major motorcycle company has, at some stage, developed a two-wheel-drive prototype. Honda, Suzuki and KTM all came close, between 1980 and 2000, to making such machines, but all opted against the idea.
Once again, the question is why? Yamaha's development work, done with Ohlins over a period of a decade, resulted in dozens of prototypes, ranging from scooters to superbikes, along with occasional, tempting hints that the idea was proving just as workable on Tarmac as off road. American pioneers Christini also saw good results with their prototype two-wheel-drive super single race bike, saying “corner speed and exit stability upon acceleration are dramatically improved” even on Tarmac. However, just as the complex two-wheel-drive system from street bikes were starting to become viable for production, another technical development – available at a fraction of the cost and providing some, if not all, of the benefits – came onto the scene: Traction control.
While technically traction control can't offer the absolute increase in grip that two-wheel drive hints at, it's cheap and simple – needing little more than a few sensors and some extra programming for a modern motorcycle's ECU. No need to redesign gearboxes, frames or suspension to accommodate costly, heavy, power-sapping two-wheel-drive systems, just add a few algorithms to the computer programming instead and you'll get many of the benefits of two-wheel drive – improved traction, less chance of crashing – for a fraction of the cost.
Even if two-wheel-drive was clearly proven to work, would you opt to spend 200,000 THB on one with two-wheel-drive, which will be slightly less powerful thanks to the power drain of the transmission? In that light, regardless of the potential gains in ultimate, wet-weather performance, it's unlikely that two-wheel drive will ever be more than a novelty.