Lot's of road rides can be found
here.
My favorite is route 2B in the Sunriver section (in reverse). Climbs out of Sunriver up to Mt. Bachelor then down through some incredible scenery past the Cascade Lakes regions.
Another nice ride is the Newberry Crater route (# 19.)
There is not a lot of services out that way (only a couple fishing 'resorts') so pack accordingly. However, the traffic is extremely light on the roads which is a nice change.