The network of trails probably frequented the most are around Edale, Hope Valley, Ladybower and the Upper Derwent reservoirs. All these trails are natural and often evolved over old ruined roman roads and bridleways and there is no way-marking so be prepared and if you can hook up with a local or club to get the best out of it.
The local trail advocacy group is Peak District MTB and you can get up to date trail conditions from the Keeper of the Peak twitter feed.

Here is a taster of some of the top routes and you can access many of these and more with GPS tracks under the GPS tab on this listing:

Doctors Gate and Cut Gate Path

Rocky and often muddy as well as exposed in places, Cut gate starts off on a descending track takes you down an old roman stone path typical of the area and down steep rock steps that are technical in places.

Stanage

This is a rocky route. Expect Gritstone flag stones, slabs & small boulders, peaty mud and grass. The Stanage steps are renowned and quite technical.

Flatttyres MTB offer guiding, skills coaching and has a rich source of trail guides with detailed descriptions and downloadable GPS tracks.
MonkeySpoon
Pegasus MTB coach in this area and the surrounding region.

If you have ridden the mountain bike trails in The Peaks then please share your experiences by posting a review, picture, GPS track or video to the listing.