Nothing its imposible!!!!! The route from San Juan to Pozuelo.
You have to ride from San Juan to Piņones then from Piņones you ride to Loiza, at Loiza you ride to take the carretera #3 in Canovanas, you can ride at carretera#3 then you can go tru Rio Grande, Luquillo(beach and some places to stay) the next day you can follow the carretera#3 to Fajardo then Ceiba and Naguabo(another beach you can stay), next day from Naguabo to Humacao , Yabucoa and Maunabo(You can visit El faro de Maunabo and stay there, another beach), next day from Maunabo to Patillas, arroyo and finally Pozuelo(Guayama).
Many places to stay at cheap prices, Pozuelo area begin at carretera #3. Then you can pay some of the nativos there to take all of you and your bicycles back to San Juan.
Have a nice trip