There is then quite a long climb (0.5 mile) up a tarmac lane (High Titten), passing the quarry on your right (Amberley chalk pit museum, in which some of a James Bond film was filmed). About 50 yards passed the Y-junction with road coming up from left, as the lane bends round to the right, there is a path to the left. It has a form of gate, and the path is very steep, though short. Definitely not cyclable, or worth cycling!
The narrow path levels off for a short distance, then after the farm track another short very steep section, again I always walk up to the top of this hill, Amberley Mount. (I think possibly steepest climb on SDW? )
[Photo below distant view from mile or so to north of Amberley Mount]
Once on the top of Amberley Mount (+160m), the SDW maintains a similar height for several miles, with only slight gradients.
The surface is also quite good, hardish gravel with only some loose stone. In fact after the roughness of Bignor Hill and Cocking, it seems positively smooth!!
PHOTO below just over top of Amberley Mount towards Rackham Hill. There is a good spot for rest lunch on bank to right of SDW at path junction just before top.
After 3 miles from Amberley Mount, you come to a car park at Chantry Post (accessible from road from Storrington) [photo below left] (looking west, masts at Bignor just visible beneath post finger) with a double obstacle [photo below right] in the form of foot high planks of wood for you to lift your bike over. Then a similar device on leaving the car park. There is also another car park before this at Springhead Hill, about 1.8 miles from Amberley Mount.
SDW is then a track in a field, heading towards a barn (0.5 mile from Chantry Post); go to the left of the barn across cattle grid, SDW goes off to the left, diagonally in photo below. Chanctonbury Ring just visible on horizon above 'field'.
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Don�t take the track which appears to go to the right of the barn and which seems to go in the right direction; it is not SDW !
There are usually cows in this field, but have always found them uninterested (and disinterested as well !) in passing of walkers, cyclists etc. Follow edge of field, keeping barbed wire fence on your left. Come out of the field at the gate. There are views of Chanctonbury Ring here. SDW goes diagonally left to right through trees in photo below. There are also the remains of WW2 gun emplacement on the left.
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Then on to a stony track, which gradually descends to the A24 ... CAUTION The steepish track changes to tarmac after a gate, then after about 100 yards there used to be a bollard right in the middle to the road , but, thanks to Paul for emailing me, the bollard has been removed BUT the 'bracket' for the bollard (approx 1cm-high square steel base) is in place. It's a reasonably fast descent, so the uninitiated could come a cropper here.
Photo below is of A24 crossing, and water tap sign.
Note that if you want to avoid this crossing of A24, there is an alternative route, 0.6 miles from the barn which crosses A24 via a bridge, and it is signed posted A24 alternative crossing, but means descending all the way down to Washington, then climbing back up again. On the BHF rides, it is mandatory to use this alternative via the bridge. See Alternative Route 1.
Photo below is of sign.
There are also some photos on the going 'Westwards' page