Let's offroad / mountain bike / mtb / ride dirt

Don't discount Epping too much, I regularly go up there as I can ride all the way up from Whitechapel using less than 1mile of road. Alternatively the overground goes straight from Liverpool st to Chongford in about 25mins.

There is some great of single track and you can easily get a 20k loop together with a tea and cake stop in the middle, man made jumps and a good little section of big bomb holes. Lots of options to for you to make you route as challengign as you want.

Speaking of man-made jumps, was going down a pretty big hill only to spot a snow ramp right in front of me, no time to react to it, was pretty awesome.