I really like the Garmin eTrex 20 and 30. The 30 allows the use of HRM and cadence sensors. Both can be found at discounts on eBay and elsewhere. Both can use either OSM (free/modifiable) or Garmin ($ for City Navigator) maps. There are more expensive/newer GPSs out there but the Etrex does most basic cycling stuff pretty well, uses replaceable +/or rechargeable AA batteries (~18-21 hour life), and can use memory expansion cards for route storage. I have yet to regret buying my eTrex.