Surrey Downs West and East are Cycle Orbital’s Everest and K2; different but challenging runs involving well over 1000ft of cumulative climbing. This is classic cycling territory, and though the route skirts Box Hill, the famous Zig Zag hill can be included via Headley Church Lane 2 and ZigZig Road 5 on the Box Hill Loop - though it should be cycled anticlockwise to make the classic climb.
From Walton it’s a descent and ascent to Headley 2 (passing under the M25; you will be outside its orbit now until Enfield Lock). R Slough Lane, Tumber St and Leech Lane, then 2.6 L for a stunning run down Lodge Bottom/Headley Lane to L 4.7 Juniper Hall (where the off-road Spoke 5 var joins from it's intrepid journey on Roman Stane Street). Under the A24 and R 5.4 (straight on NCN22 for Spinoff 7) and after Boxhill and West Humble 5.7, L at 6.6 for Ranmore Common.
This and its counterpart at Shere in 7 miles are the big climbs of the circuit. The Ranmore climb in particular is steeper and tougher than the Box Hill ZigZag. You are on Surrey Cycleway, which sticks with the quite busy road at the top, but after Ranmore Common, one of the great Cycle Orbital discoveries is a byway, an old drove road, of forest tracks starting L 9.6*, re-joining the road at Coombe Lane 13.2. Unfortunately the first half mile is near-impassable, due to a giant puddle and degradation. Currently therefore stay on the road and turn L 9.9* at Whitedown Lane, regaining the drove road 10.1. You now enter the most remote section of Cycle Orbital. It is actively forested country and there may be rough sections to start, but the conditions get steadily better, ending in a metalled surface. On a revisit (Oct 2020) these three miles were in a much better state than at first recce - good news!
At 11.8 Netley Heath there stood a telegraph station on the Optical Telegraph of 1795 for messages relayed from the Admiralty to Portsmouth. Being close to the scarp edge viewpoints and picnic spots crop up. Before the descent to Clandon, if the visibility is good, make sure you take in the enormous panorama of the London Basin 13.8 – or visit remote Tillingbourne Brewery L. Test your brakes; you will reach 30mph+ once you have got to know the road, its curves and surface.
*If conditions are very unfavourable, or your bike a ‘thoroughbred’, stay on Crocknorth Road, descending towards East Horsley and climbing back on Green Dene. This Surrey Cycleway route is often busy, not particularly rewarding, and involves a steep descent and immediate re-ascent to no great purpose.