Ramsey county has several bicycle and trail maps online, but they're poorly organized and hard to find. These links may not persist, but they are a start:
Ramsey County ALRC: Active Living Ramsey Communities
Ramsey County Bike facilities and Gaps map (PDF)
They have some Google maps "rambletown tours -- not terribly useful, but nice to see ...
Now you can visit Ramsey County's Gateway, Bruce Vento, and Indian Mounds trails from your computer. These maps are created from a web application that automatically generates trail maps from pictures on a web album that have been geocoded.
Other sites list more maps
Pedestrian Trails Map (5 mb PDF file)
Hiking and Biking Trail Information (pdf)
then there are regional trails
Lastsly, there's a Hiking and Biking brochure.