If speed endurance is what you are looking to build, Drift Road offers a long flat straight.
The Henry VIII gravel loop extends the Chartwell loop. Rather than heading over to Chartwell and Toys Hill, it heads further south to Hever Castle (home of the Boleyns hence the route name), Chiddingstone castle & village before a steep climb up Yorks Hill and the return leg to Surrey.
The Wendover Loop cycling route takes a steady climb out of West London, leaving London north of Uxbridge before heading into the heart of the Chilterns.
The Surrey Trails & Hills gravel route heads down to the Box Hill area for a loop before continuing on to Ranmore Common, White Downs and Effingham Forest.
The London to Whitstable one-way cycling route heads south over Crystal Palace, out of London, before the climb up the side of Biggin Hill.
The Redhill Aerodrome Circuit cycling route heads south from Hampton Court Bridge, up over Box Hill before heading further south with a loop south of Reigate. There is an opportunity to stop at Redhill Aerodrome’s café to watch light aircraft take off and land. The route then heads north towards Kingston.