Box Hill Mountain Bike Trails
Box Hill is part of the North Downs chalk ridge and the Zig Zag road to the top is a mecca for road cyclists after featuring in the 2012 Olympic road race.
It has plenty to offer mountain bikers with some of the longest climbs in the area (if you're into climbs) and plenty of routes down. Note though that there are no official mountain bike trails on Box Hill.
Box Hill is managed by the National Trust and is also hugely popular with day-trippers from London with superb views over the south of England from the main view point.
There are toilets and a hatch at the top serving refreshments year-round. The queue for this can be length at a weekend. The car park at the top is regularly full on a weekend too so I would recommend cycling there rather than trying to park there to start your ride.