I encountered the following two sentences in my Italian Rosetta Stone program:
Vanno a cavallo sulla spiaggia.
Va in bicicletta sulla spiaggia.
However, I can't understand why the former uses a
while the latter uses in
in preposition. Both use andare
and express what to ride in to andare in spiaggia.
Is there any explicit criterion on when to use in
vs a
in andare?