Toothed-belt drive.
Extra quiet but highly durable too.
The innovative rear axle differential whereby a toothed belt conducts the engine power to the rear wheel ensures clean, low-maintenance power transmission. Together with the single swinging arm made from light alloy, this represents a first in motorcycle design. With this combination, the secondary drive is equivalent to the clean, low-maintenance cardan shaft drive. Developed specially for BMW Motorrad, the toothed belt not only runs particularly quietly but has also proven to be highly durable due to its aramid fibre reinforcement.
After the correct tension has been set during the initial inspection, an inspection is performed every 10,000 kilometres, with routine replacement occurring after 40,000 kilometres. The toothed belt is tensioned via the eccentric shaft, in which the rear wheel is guided in the single swinging arm. This single swinging arm also ensures that the rear wheel is aligned perfectly in longitudinal direction.
Since the toothed belt is constantly tensioned, any possible load change reactions are minimised, which is hugely beneficial compared to a conventional chain drive. Load change reactions are additionally reduced by a damper equipped with four elastomer blocks. The toothed belt drive, which is manufactured from stainless steel and the gearbox output pinion with an inner steel core ensures the longevity of the drive. The gear ring is made of a sintered metal alloy. All in all, this combination ensures the least possible wear. Due to the secondary drive having a lighter design than the chain drive overall, centrifugal forces are lower, which improves the power transmission efficiency.
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