Thievery is not a major concern here... bicycles all over the yard is. This is not a security measure as much as a housekeeping issue- you can get through 1" schedule 40 PVC with double-action garden pruning loppers.
I am using greypipe PVC conduit for the long parts and white PVC "T" junctions- the greypipe is UV resistant and cheaper. The "T" junctions will have to be painted... they are not available in grey, as conduit is for romex, not water. From a gluing standpoint, there is not much issue- this will not be holding water pressure. If you figure 20 "T" joints per two bicycles (always even numbers with this design) you can start to calculate how much this might cost you... insofar as how much pipe... well, I'm still working on it.