Girdlestone, who was third in 2011 and second last year, secured victory at the eight-day stage race in Kigali on Sunday.
The Westvaal-BMC rider, representing the SA national team in Rwanda, has signed for Team Bonitas next year, and after taking on a full-time job in April, he is eager to compete on the French circuit with his new trade outfit.
“Westvaal-BMC is the best team I’ve ridden for so far,” Girdlestone said.
“They’ve created a great environment for their cyclists, but they don’t offer international competition, which is why I’ve made the switch.”
The 24-year-old rider, who works at the VeloLife cycle shop in Pretoria, was delighted to grab the overall win in Rwanda with the national team, which also included Paul van Zweel, Kevin Patten, Stefan Ihlenfeldt and Nico Thiart.
“It was a big relief. I said to myself that I was going to make it happen, so I was really happy to win.
“It made it even sweeter that I won against MTN-Qhubeka, the team I rode for in 2010 and 2011.”
While MTN-Qhubeka lost early leader Jay Thomson due to illness, Girdlestone believed the SA team would have secured victory nonetheless.
Louis Meintjies, representing the pro-continental trade outfit, finished second overall in the general classification.