Create links from each world (Watopia, London etc.) Through a 1km? transit tunnel (time tunnel, warp tunnel, whatever sounds coolest) to a flat core ring.
The tunnels could be futuristic to ignore distance/ physics or decorated like airport conveyors with themes of the destination. The Core would be the centre of the earth, basically a giant roundabout with junctions back to each world. Junctions every 500m? (Whats the min distance on normal routes?) A pretty glowing ball or science atom structure in the centre… imagination run wild. Maybe just Zwifts big pile of subscription cash?
Scope for all sorts like a 360km straight line loop at 1% climb both directions (ride the ring).
Would be very cool and a better way to transit between worlds than exiting the game… maybe even create the ultimate linked route.