I'm in Northallerton, but I doubt I'd be able to ride. I mean I am seriously unfit, out of breath climbing stairs unfit.
I did used to do that, pick out likely routes. In the south, I once spotted what looked like a decent twisty downhill track in a small woods just west of where the M25 breaches the North Downs escarpment. I tried it one cold winter's afternoon, entering the woods required a quick hop over what many would describe as a barb wire fence indicating some sort of land ownership boundary, but such things did not worry a free-thinking radical like I was back then.
The downhill was less thrilling than I had hoped for but soon the land opened out in soft rolling greenery, almost Capability Brown-like in its appearance. As I crested a small rise there in front was a massive country residence, Rennaisance style, and looking very much like I was tresapssing at this point. I sidetracked it and exited the grounds through the stables, pretty damn sharpish.
Turned out it was Chevening House and the offical residence of the Foreign Secretary. I can confirm that security was quite slack.
Edit: Funnily enough, Hague lives there now, maybe I should complete the circle and leave some tyre tracks in his back garden up here.