I have always assumed that the centre line of the bevel box drive belt pulley is exactly on the swinging arm pivot point. Designing it to be close enough would be a pointless exercise when there seems to be no reason for it not to be exact (engineering tolerances aside), allowing belt tension to remain constant throughout suspension travel range.
Richard,
I only said "close to the centerline" because I've read here that it may not be exactly on centerline with the BB shaft.
But I do stand by my point, and that was that it's close enough to not make a difference in belt tension when the swingarm is up or down from ride height.
