I lived in Cambridgeport for a while. Now I commute to Kendall Sq. everyday by bike from Brookline. Cambridge is very bike friendly. Brookline not so much. For repairs, check out Broadway Bicycle School. For clothing, check out REI in Fenway (Boston, not Cambridge) or Landry's on Comm Ave just west of the BU bridge (an easy ride from Cambridgeport).

Mark