The Bestmed Masters team completed the 59km final stage, which included 920m of ascent, in 2:19:52 to lift the title in 7:36:27.
Gauteng Dairy’s Charles Steyn and Ian McLeod, who won stage one, finished runners-up on the final day in 2:24:11 to consolidate their second place in the standings in 7:41:38.
Last year’s champion, Gertjie Harmse, who rode with his brother Louis in the colours of SS Timing-ASG, completed the day’s podium in 2:24:59 to seal the same place in the general classification in 7:54:09.
Mapstone and Benson, who trailed Steyn and McLeod by just over a minute after the first day, made the most of a technical section around 6km into the 51km second stage to surge into the lead.
“We got away going down a big rocky decent and just kept our heads down,” said Mapstone, who is from Pretoria.
