In Theory it should be possible to buy a ticket Lausanne - Chur, and then send your bike, as a piece of luggage, via the SBB luggage service.
While you are required to have a ticket, you are not required to actually board a train, and SBB has no way of knowing that you did not do so.
(I wonder what would happen if one bought a ticket, then send off some luggage, then cancelled the ticket again…)
