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.
MarkC screwed with this post 03-06-2007 at 08:52 AM