Here's a link. http://www.hbl.org/maps/maps.html
The map is hard to read on the computer, but if you go to Island Triathlon and Bike on Kapahulu, close to Waikiki, or any other bike shop here they have the maps. There is a good route from Waikiki, around Diamond Head and out to Waimanalo. You can go around the island if you want. There are only a couple of roads that would be kinda sketchy. Have a good trip.