Also you could head upto Wirksworth, not too far from Ashbourne…cyclable if you’re really keen, but only 20 mins in a car, and there you’ll find Black Rocks…lots of DH trails about 2 – 3 minutes long. We just tend to loop them, and grunt unto the Trig point where there is another fantastic descent or two. You can spend as long or short a time as you like around there because you’re looping lots of trails so can call it quits whenever you like or if the conditions are not great.
You can then drop down the incline, mooch along the canal path towards Ambergate and you’ll find loads of similar trails there. Not sure Ambergate is that good at the moment…last summer the forestry commission were clearing trees so carved up the ground so we’ve not been back since, but there are other areas and trails in that vicinity.
No idea how best to tell you where the trails are…I could try to export some GXP files for you if you decide to head out that way.