I did a 3000+ meter ride in 50ish miles a few months back. Its easily doable if you link together Goyt Valley, Hayfield, Chinley, Macc Forest, Edale etc etc.
EDIT – it was actually closer to 2,600m in 54 miles. I headed back home then but my friend stayed out for an extra 15 miles or so and did over 3,100m