In answer to a question on another thread, there are a lot of public rights of way in the whole community of Madrid, known as Vias Pecuarias. The web site is

http://www.madrid.org/ceconomia/agricultura/html/pagprincipal.html

Vias Pecuarias were originally tracks used to move livestock from one area to another, but as this is dying down the Madrid council is trying to create a network of paths for non-motorised leisure use.

What I tend to do is use the map to find roughly where they are, then just cycle along them until I run out of steam, which doesn't take me too long, or they are blocked by farmers who don't like people using them although they have no right to block them (this can be done by either the use of fences or sometimes by putting bulls in the field so keep your eyes open !), or they become difficult to follow or even just fade out.

There are other cycling web sites with GPS routes available for download, and if you google MTB they come up, but at the moment they seem to be for people far fitter than I am, so I haven't tried them - maybe one day.

If anyone has any favourite routes I would be interested to learn of them.