It is indeed a very big place.

But this fellah seemed to have that part figured out: Bike to the train station, and take the bike on the train. That part seems straight-forward. The train stations were near-enough to where they wanted to start, and near-enough to where they wanted to be.

The problems they lament seem to revolve chiefly around the specifics of taking the bike on a train, and the limited schedule of the train, and the lack of adhesion to that schedule.

Those problems wouldn't be improved if the vastness of the US were reduced, would they?