Roland, there are plenty of places to rent bikes on PP, make sure you check the condition with a short trip before heading bush, bikes vary in price for condition, USd$10 per day usually, you pay youself to put in new tubes, tyres (they are always patched) punctures are a bitch in the bush. the Gecko Cambodia map is the best , available in country for once again USD$10. Anywher outside the cities is beautiful, try Preah Vihear temple, Ratanakiri province, the Crdamoms are also nice, check out Toursintheextreme.com
Harri.