Cannondale make some excellent bikes even in the 80's. I have a newer one (92) thats a touring bike 24 speed and its worth around $600. I have fixed and sold a lot of road bikes and i would say yours is worth at least $250 if its in good condition, meaning no rust and has good tires and shift nice. If the frame is really lite, like 23 lbs or less it may be worth more. If it feels heavy, like over 27 lbs it probably not worth more then $200. People pay more money the lighter the frame. If it says Champion frame search on the net and find out what bikes that have those frames go for. I sold a lot of road bikes with 27 inch wheels and their good bikes.