As you may know, Le Marche is characterized by alternating ridges and river valleys descending from the Apennines to the sea. There is a coastal band, which is narrow in places and fairly wide in other places. This band is rather densely populated and more or less industrialized. Then there is a band of foothills, with small walled hill towns and farmland, and, finally the mountainous zone. The best cycling is found in the foothills, where the ridges aren't so high that you would have long climbs to go from one valley to another, and where there are lots of small roads without a lot of vehicle traffic.
Pesaro, Gabbice Mare, the park of Monte San Bartolo, inland from Fano, Fossombrone, Monterado or Mondavio, Corinaldo, Barbara, or Castelleone di Suasa, Belvedere Ostrense Morro d'Alba and San Marcello, the regional park of Monte Conero, Osimo, Offagna, Castelfidardo, upper Potenza river valley, Matelica .
Here are two web sites, in Italian, with advice about cycling itineraries in the province of Pesaro:
Both have itinerary maps, which should be understandable without translation.
Here is a very complete list of bike itineraries for all the provinces in Le Marche:
Via Mariano Pallottini