Toothed belt drive with single-sided swing arm

The innovative rear wheel drive, in which a toothed belt transfers engine power to the rear wheel, ensures clean and maintenance-free power. Together with a single-side swing arm in light alloy, it is a truly unique motorcycle design. This combination in a secondary drive equals the clean and low-maintenance shaft drive of the R and K Series. Specially developed for BMW Motorrad, the 26 mm wide toothed belt (dimension 11M-1892-26) not only runs extremely quietly, but it is also extremely durable due to its aramide fiber reinforcement. Once the correct tension has been set during the first service, it no longer requires servicing right up until it replacement - after approximately 60,000 KMs. The toothed belt is tightened over the bearing which guides the rear wheel in the single-sided swing arm. The mono swing arm ensures that the rear wheel is always positioned perfectly.

Since the belt is constantly under tension, possible load change reactions are minimized. This is a great advantage when compared to conventional chain drive. The load change reactions are additionally reduced by means of a jerk damper fitted with four elastomer blocks. The durability of the drive system is ensured by the toothed belt wheel in stainless steel and the output pinion gear which has a steel inner core; the sprocket consists of a sintered metal alloy. This combination ensures minimum wear. Due to the weight saving compared to chain drive, centrifugal forces are also reduced, thus improving the efficiency of power transmission.

Suspension using a single-sided swing arm is a well-known BMW trade mark and for good reason: it makes the wheel easier to remove and can be designed for extreme twist resistance and lightness. When used in combination with the toothed belt, the swing arm is made of light alloy chill casting. Once the central nut has been released, the rear wheel can easily be removed - in order to change the tire, for example. The correct tension of the toothed belt is retained. Due to its wide design, the unconventional rear wheel suspension ensures that the rear wheel is always correctly fixed lengthwise. The rear gear wheel, toothed belt and front pinion are thus also automatically flush. At the front, the single-sided swing arm is on the same axle which connects the engine to the chassis, pivoted by means of maintenance-free and sealed needle bearings. Unique in motorcycle construction, the belt drive and single-sided swing arm combine their benefits and make motorcycling even more trouble-free.