How Yamaha’s 2WD works

Published: 09 December 2001

Ohlins/Yamaha’s system is light and so simple it can be fitted to virtually any bike with minimal modifications to the standard suspension and transmission.

It uses hydraulic pressure to transmit the power to the front.

A small hydraulic pump is attached to the engine, and driven by an extra chain running from the front sprocket of the stock gearbox. It uses six or more tiny pistons to pump hydraulic fluid through flexible, Kevlar-reinforced hoses to a hydraulic motor mounted on the front hub. This simply turns the wheel via a cog mounted inside the hub.

Because the pump is driven from the gearbox sprocket, the front wheel can never turn faster than the rear – so it won’t spin. But, if the rear tyre loses grip and spins, the pump will run faster – increasing the hydraulic pressure and therefore the amount of power going to the front wheel.

The use of hydraulics limits the amount of power to the front wheel. But insiders claim as much as 20 per cent of the bike’s power – around 30bhp – goes to the front of the R1 prototype.

Once in full production, there is little reason to expect a design like the Ohlins/Yamaha idea to add more than a couple of hundred pounds to the cost of a production bike fitted with the system.