I've been mapping Denver Metro bike trails for two years now with a GPS.

GPS maps have a number of advantages over paper maps:

• It knows where you are
• Can warn you of upcoming turn/missed turn
• No folding/unfolding requuired
• Paper maps are out of date before they are printed
• Paper maps do not allow you to zoom in for more detail
• Paper maps offset trail from real location for clarity
• Electronic maps can be modified repeatedly as often as desired/needed

Have "mapped" over 550 miles of metro trails condensing them into 35 trails.

Gps_dr website

Unlike many/most of the Colorado trails available on-line or in print, these trails are:

• Not Mt bike trails (With exception of Heyden/Green Mtn trail)
• Rideable most of the year
• All trails connect to other trails
• Can be ridden by a wide variety of fitness levels
• Route descriptions are available in text & spreadsheet formats.
• Routes/Waypoints/Tracklogs uploadable in a variety of formats
• Free

The trails are designed to create a network around the Denver area and of course do not include all of the on/off street trails and bike lanes.
For simplicity, I've connected various trails/trail segments together.
For connectivity, I've added extensions to existing trails as needed.
For use on the widest range of GPS recievers:

• Limited the length of each tracklog to 250 pts each
• Limited waypoint names to 6 characters
• Limited routes to 30 waypoints

I use paper and on-line maps along with DeLorme Topo USA 5 to plan new trails.
I also use it to create a proprosed ride track that I upload. When I get back I edit to remove the enevitable mis-turns etc. I do carry a paper map or two on exporatory trips.

Happy GPS Biking