The 30-year-old Welshman is training until Sunday in South Africa’s northeast, near Pilgrim's Rest, at 1700 metres. The thin air and efforts should prepare him for one of his biggest seasons yet, in which he will lead Sky along with Spaniard Mikel Landa in the Giro d'Italia, May 5 to 28.
"It certainly feels a hell of a lot different," Thomas told Cycling Weekly. "Everything is a lot more surrounding the first part of the year with this camp, racing and recons."
He will return next Sunday from the camp and recover at home. He will travel to Italy for Tirreno-Adriatico, March 8 to 14, and Spain for the Volta a Catalunya, March 20 to 26.
"So after Catalunya, I will have a week at home, and then a two-week altitude camp and then go straight into Trentino [Tour of the Alps, April 17-21]."
In recent years, many favourites including Bradley Wiggins have used the Trentino race through the Dolomites as a Giro springboard.
The race usually covers some of the Giro's high passes and is near enough to many others for a quick reconnaissance trip.
Thomas's reconnaissance of the Giro will include the main 39.2km time trial through Umbria before Tirreno-Adriatico and the Blockhaus summit finish stage afterwards.
"I already know the Mortirolo and Stelvio," he added. "Of the final three mountain stages, I will see probably not all of them but definitely a couple of them after Trentino."
The Giro route will properly visit the Dolomites with a heavy stage to Ortisei on stage 18, finish up Piancavallo on stage 19 and climb to Asiago on stage 20.
It will end the next day with a favourable 28km time trial from the Monza Formula One track to Milan's Duomo cathedral.
Thomas's preparation for those efforts starts 8000 miles away in a national reserve. In 2015, Froome trained with Wout Poels, in 2016, Ian Boswell provided company, and in 2017, Thomas decided to visit.
"This is the first time that it's been an official team camp with just the two of us,” Thomas said.
"It's just me and Froomey, and so there's no better guy to chase around.”
Sky sent coach Tim Kerrison, a mechanic and a soigneur to accompany its two stars over the two weeks.
Thomas will have around 10 training days and a couple reset days. Most mornings, he is awake with Froome around 7am and riding already at 8:30am.
"We'll start to put some efforts in there and build with a bit more intensity. More intensity given that we're in February already. It's just a solid little block, nothing to worry about but just riding your bike, massages, eating well and resting really well."
The Welshman has known Froome since they raced together in Barloworld in 2008 and 2009. In those years, no one considered Froome would go on to dominate Grand Tours and win three editions of the Tour de France.
Watch: Geraint Thomas's greatest win
Thomas helped Froome win his three titles and to other success, but it could be that in these two weeks he gains even more knowledge.
"Obviously, you chat about everything from training to diet to focus and that. It's good to get together and just be super focused. We're both motivated to get stuck in and do more every day,” added Thomas.
"We are able to test each other and push each other. If one is a bit tired then the other can drag them out and gets more out of a person."
Thomas, now married, has had time to reflect on 2016, too. Last year, he switched fully from the Classics to stage races. He won Paris-Nice and began the Tour as Sky's plan B.
The Tour went well, but not as well as Thomas had hoped. He placed 15th overall.
"I think the main thing with last year was over-training a bit, or under-resting really. And the whole diet thing," Thomas continued.
"That's a thing I need to remember. After this camp, I will need to rest properly and have a couple days training but not really go push it. Sometimes you end up pushing too much and going over. That is a constant thing that you need to keep reminding yourself about.
"I will ride Tirreno-Adriatico and then Catalunya. No matter what happens after those races, I just need to rest up properly and keep reminding myself about that."
The scale showed Thomas at 69 kilograms on Friday morning. He said that he is "a good solid 70."
“I am just trying to be a bit more consistent with it and more steady. I think I just lost a bit of weight too soon and too quickly too close to the [Tour]," Thomas added.
"So I'm just going to try to do it that bit more consistently. I just need to keep working hard and keep eating well. And just not try to go into the extreme and try to do anything too quickly or too drastic. I don't think I need to be as light as I can for a Grand Tour."
Since Rigoberto Urán rode to second overall, Sky have not had the best of luck in the Giro d'Italia. They tried to win with Bradley Wiggins, Richie Porte and last year, Landa, but failed to do so.
Porte pulled out due to a crash in 2015 and Landa due to stomach problems in 2016. Simply arriving to Milan for the finish of what is the 100th edition of the Giro d'Italia would be a success for Sky's leaders.
"I'd be happy with winning! I'd be happy to be on the podium as well. Or a top five or even a top-10 would be the best result that I've had in a Grand Tour," Thomas added.
“It's a good opportunity for me even if the GC burst apart I would even have a chance to go for stages. It's just nice to have a different program now and a different objective, and new goals."
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