No links but about a thousand routes Same with the rail beds. However buy this book...NOW!...because it's out of print. It's got nearly every railroad and railroad spur in the state in it. A lot of the routes are on public land and easy to access.

In addition to the routes mentioned above, some of the better road tours would be:

Estes Park to Grand Lake/Shadow Mountain Res and back. It's only got a 12,000 foot crossing of the mountains in the middle of it that you have to do twice

Durango to Silverton (not that close but beyond spectacular) then on to Ouray (Beyond spectacular to breath taking...literally and figuratively) and Ridgeway (relatively boring) around to Telluride and back through Dove Valley to Durango would be a glorious 4 or 5 day trip.

Salida to Saguache to Gunnison and back to Salida would be a nice 4 day trip. If you wanted you could push further north to Aspen and come back over Independence Pass.

There are some in the Denver area but traffic is higher along the Front Range so routing is a but tougher.

A very nice 2 or 3 day trip would be to start in Trinidad, ride north to Walsenburg, west to La Veta then over Cuchara Pass and back to Trinidad. Some riding on I-25 but Cuchara Pass and Stone Wall are worth the traffic noise.

I have a whole bunch of other ones including some trips into the 4 Corners regions and a trip to the largest dinosaur trackway in North America. Just a taste of the trackway trip which I do nearly every fall