So I wasnt sure if I should post here, or in this thread Disk Brake choice for new Nimbus hub. It kind of relates to both topics, so I decided on this thread because it is not as old. I also would like to say that I am not going to try this, but somebody else may find it useful.
Obviously, there is not enough clearance to use a mechanical caliper on outboard disks, and it appeared that there was not enough clearance to use mechanicals on one of the inboard Nimbus disk hubs (there were pictures from Ben, but they are no longer there). I am curious if someone could use spirit cranks with a left side inboard disk? There is more clearance with spirits than moments, so it seems it may work. If someone wants to use a meachanical disk brake, than this may be something to look into.