OUDENAARDE, Belgium (VN) — Whoever wins the Ronde van Vlaanderen on Sunday will be victorious thanks to strong teammates, stronger legs and a bit a luck.

Another critical factor in the twists and turns of the Tour of Flanders is positioning. You won’t win the Ronde if you’re caught on a traffic jam on the Koppenberg.

“In a race like Flanders, positioning is the key to victory,” said CCC Team helper Micky Schar. “Sometimes on the climbs we are not going too hard because the real effort came before the climb.”

The Ronde is punctuated by a series of the famous cobblestoned bergs. They pock the Flandrian countryside like a series of molehills that turn into mountains when they’re stacked up at the hard end of six hours of racing. Some of the slender farm roads are so narrow that it’s hard to fit more than two riders abreast. Add the demands of the cobblestones and race speed, and everyone knows that the only place to be is at the front.

“The position is 80 percent of Flanders,” said 2015 winner Alexander Kristoff (UAE-Team Emirates). “You still have to have the legs to climb up it, but if you are not there at the front, you have no chance.”

The longer distance of Flanders turns it into a strongman’s race when only the burliest can hope to survive more than 250km of racing. By the final hour of racing, the peloton has usually atrophied to a man-to-man battle over the closing climbs.

Up to that point, however, favorites must count on their teammates to keep them at the front of the bunch heading into the critical points of the race. Any error can cost valuable energy and doom even the best legs to the middle of the pack.

Teams line up the approaches to the major climbs as if they’re leading out a sprint.

“Positioning is everything in Flanders,” said Bahrain-Merida’s Heinrich Haussler. “I’m not saying if you’re in sh—t form you can win the race, but by knowing the course, positioning yourself perfectly, and knowing where to ride hard, you can go really deep in Flanders without spending massive energy. Knowing the course is a massive, massive advantage.”

Every team brings a few veterans who know the roads of Flanders. Iljo Keisse, one of Deceuninck-Quick-Step’s top helpers, has been racing and training on the Flanders bergs since he was a teenager. His job is to use that local knowledge and pilot the team’s leaders in safe position heading into the most important climbs of the race.

“There are some key points of the race where you need to be at the front,” Keisse said. “If you’re behind the front wheels, and there is a space, you are wasting energy chasing back. In a race as hard as Flanders, positioning is very important.”

Keisse ID’d a few key points. The first major breaking point comes at Muur-Kapelmuur at 170km. Though still far from the finale, the famous climb is where the first major accelerations come from the favorites.

“You can see the pack start to break apart there,” Keisse said. “The differences are so small now between the top guys that if you having to chase back, you will not be as fresh as the riders at the front.”

Being at the front over the first of two passages over the Paterberg-Oude Kwaremont is especially important as Flanders roars into the decisive final hour of racing. That’s when the real attacks start in earnest, and any misstep is costly.

“The second time up Kwaremont, that’s where the race ends for three-quarters of the peloton, and for one-quarter of the peloton, that’s where it starts,” said Dimension Data’s Bernard Eisel. “Even if you’re still in the race, you’re just a victim if you’re in the back of the bunch at that point.”

The narrow and steep Koppenberg at about 220km is another important choking point in the race. The cobbles there are so steep and long that any bobble within the bunch can see the peloton come to a complete log-jam, with riders forced to step out of the pedals and even run up the hill.

From there, the bergs come in quick succession with the first selections being made, with the rough Taaienberg sector often serving as a springboard toward victory.

From that point on, anyone caught out of position and trying to chase back from one or two groups back will have almost no chance of victory.

“You know where you have to be at the front, and we are going flat-out like in a sprint to approach the key moments,” Schar said. “If you are behind in these moments, it is very hard to be able to come back.”

Flanders is so hard that half the battle is being at the front. The rest of the race is trying to stay there all the way to Oudenaarde.