Originally Posted by MarkC
As I wrote earlier, the idea of centering the swing arm pivot at the output shaft would be ideal for using a belt setup that can be fully enclosed for protection from mud, gravel etc. (think F800GS) The enclosure can be attached to or partially incorporated into (a single sided for example) the swing arm since there is no tensioner needed.
The point being that in the above use, getting to the counter sprocket wont be needed nearly as much, as it will likely last for several 10s of thousands of miles. The worst will be having to remove the swing arm, but if it last 40K miles (belt drive), it's not a big deal. OTOH: if this is designed to work with a chain and sprocket as in the pics, then changing out the sprocket could be more of a hassle pending how BMW designs the final product.
You sure seem sold on belt drive for dirt bikes but I'm not convinced. So you add the complexity of an enclosed system (already been tried with chains, look at some of the 1970's ISDT bikes) and what do you gain? Nada. I don't have to oil it, big deal. There's a very good reason that you don't see belt drive on dirt bikes (don't tell me about Buell, I'm talking dirt), they don't work. Chain drive is the most reliable, efficient, light weight drive system... period. You talk as if the F800GS is a done-deal with belt, if that's the case they'll sure scare me away.