Grotts (Specialized) outclassed Christoph Sauser (Specialized) and Matthys Beukes (PYGA / Euro Steel) to win in 2:08:08.
The 55km route with some 1 250m of climbing featured some of the finest trails in the Greater Simonsberg Conservancy.
Beukes set the pace early, making his intentions clear, with the likes of Lourens Luus and David George, in the bunch with Grotts and Sauser.
“Matthys threw in a really strong effort on probably the longest climb on the course,” Grotts said.
“After that it was just him, Christoph and myself.”
Grotts, Sauser and Beukes rode together through the spectacular singletrack trails of Knorhoek, and it was after the last spectator point – with less than 20km to go – that Beukes tried to break up the final big climb of the day.
“I went with him, counter-attacked and managed to get away,” Grotts said.
“From there it was just a full on effort to the finish.”
Grotts stayed away with Sauser and Beukes finishing just over a minute back.
If Grotts rode alone for the last part of the race, women’s winner, Stenerhag (CBC/Åbro), spent all morning alone.
Stenerhag led from start to finish to successfully defend her title ahead of the South African duo of Mariske Strauss and Cherie Redecker.
“I got a good start and was ahead of Mariske,” said Stenerhag.
“But then at the second water point I heard I had only 30 seconds, so I realised I had to pace it a little bit,” she said.
“After that I heard I had stretched the lead to two minutes and it stayed like that from there,” Stenerhag said.