Broken Cycle — A. Bertram Chandler

Being lost in space was no new experience to John Grimes, whose career as an interstellar officer had brought him into many such dilemmas. But being lost inside a colossal alien spacecraft had no precedent.

Complicating the matter was the discovery that the very universe was not their own but an alternate and that their captor seemed to be the omnipotent force of that entire other cosmos.
As Grime's only companion was the comely policewoman, Una Freeman, the fate that the Alien God selected for them required the creation of a Garden of Eden. But there were two serpents in this one - both of them bicycles!