Froome is finishing his last phases of preparation for a crack at his first Giro title. He previewed two important stages this weekend and began the Tour of the Alps in Italy on Monday.
"Everything is different in Italy, we are not used to it, but it's not a big deal," Portal told Cycling Weekly.
"We need to be a bit more focused and make sure we are at the front, we can't be surprised and we need to anticipate."
After four Tour de France titles and the Vuelta a España victory in 2017, Froome is trying to become one of the few to win all three Grand Tours. It is his first attempt to try to win the Giro, which starts two months ahead of the Tour.
Given the dominance of Sky in the Tour, first with Bradley Wiggins in 2012 and with Froome's four titles, the group became accustomed to the race.
"Maybe in the Tour or Vuelta, we can back off a bit because we know the roads a bit. In the beginning in 2012 and 2013, the guys were always at the front because they were getting used to it. Now they know how to race the Tour de France," Portal said.
"This is probably what they don't have yet in the Giro, especially for Froome, myself and this group. We just need to be sure and make an effort to be at the front. Tactically, at the end of the day, it just goes up and down and the strongest wins. I hope it's Chris and if we don't make a mistake, he should be fine."
Much changes from the Giro to the Tour. The Italians roads are known for their potholes and poor condition. Even if they are freshly paved for the country's famous race, they twist and turn often in the undulating country that lacks the expansive plains of France or Spain.
"It's a different kind of road, the style of racing changes for sure. In France or Spain, you have certain sizes of road, but here you can have national or departmental road, and boom, it goes to one lane or opens up again. The guys can't switch off, they have to be on all the time. The bunch will be in four or five lines lines and then boom, in three lines. You need to be active in Italy," Portal said.
"We do the recon it's just to get a good feel, more than just looking at maps and video. It good, you can really feel how hard the climb is. Not just the Zoncolan, but the run in. It's going to be a hard stage. There are three climbs before the Zoncolan, and some of them are pretty steep. The thing is the downhill, it's twisty to the run in to the Zoncolan. If the weather is cloudy and rainy, it could be a comply different day."
Portal last directed Sky's Giro team when they raced in 2012 with Mark Cavendish and Rigoberto Urán, while Froome has not lined up since 2010. The reconnaissance, Tirreno-Adriatico and the Tour of the Alps, will give the group the Italian flavour they need before the Giro starts on May 4 in Israel.
Portal with trainer Tim Kerrision and mechanic Gary Blem followed Froome through the reconnaissance this weekend.
When Portal saw Froome, he was impressed. Since he lost time on the Tirreno-Adriatico's summit finish stage and finished 34th overall, things have changed. Portal said, "Yeah, we are looking at the Tour de France Froome, now."
They covered the last 90 kilometre of the Zoncolan stage, the Giro's 14th on May 19. They rode the famous 22 per cent pitches of the final climb to the tunnel, one kilometre from the top, where the snow blocked the road. The next day, they rode the 34.5-kilometre time trial to Rovereto.
After the Tour of the Alps, Portal will help select the team with boss David Brailsford.
"We have Vasil Kiryienka, Christian Knees, David López, why not Tao Geoghegan Hart? The selection's not finished yet. And the climbers too: Diego Rosa, Sergio Henao, Kenny Elissonde, Wout Poels.... Salvatore Puccio will be a key element, too.
"They have all been preparing for the Giro. It's not going to be easy to select the seven around Froome."
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