Some repeat suggestions by othres.
Show all roads in background with the bike routes highlighted.
Differentiate by colors all trails, roads with bike lanes, bikes on sidewalks, roads with shoulders, low traffic roads, and other bike roads that might require more skill or attention from the rider.
Also show roads that bikes are not permitted on, and maybe the roads too dangerous to bike and special hazzards.
Green halftone background for parks, greenspaces, schools, etc.
Landmarks: downtowns, shopping centers, libraries, hospitals, museums, beaches, water, scenic overlooks, etc. Maybe use a grey halftone for commercial areas and blue halftone for water.
Toilets and water available on route.
If you are selling advertising, bike shops, taxi, restaurants and stores.
Some way of indicating hills and steep grades. Maybe using < for a mild grade, <<<< for a steep one.
Local bike regulations in a side bar.
Emergency contact numbers for local police, rescue, hospitals.
Give official, and even unofficial names for the bike routes.
Location of mileage makers on major trails. Some mark for mileage on other routes. Perhaps a dot on the line indicating the trail.
Include the date that the map information was last verified. I hate maps that I can't find out how old the info is.
Will the map be on-line or paper?