The 2021 Vuelta a España covers three weeks starting on August 14 in Burgos, features nine summit finishes and a time trial to begin and end the race September 5. FloBikes looks at six critical stages this year's grand tour.

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Stage 3

The first summit finish to Picón Blanco will indicate who has the legs to win this Vuelta a España edition. It's a short climb of 7.2km, but has 17% grades. For example, Picón Blanco could reveal who is the true leader of teams like Ineos Grenadiers and Movistar. And show us out of the hand full of underdogs, who could seriously challenge for the final podium spot.

Stage 5

The 184.4km stage to Albacete is one of those typical Spanish stages that could explode into echelons. Travelling south, the road is continuously exposed and presenting problems for those small climbers who lack a big support team. This is where we can expect to see Egan Bernal with Ineos support excel. Or see Primoz Roglic rely on his Dutch team to make gains -- not on the climbs -- but on the big wide Spanish roads.

Stage 9

This is going to be a big day with 4500 meters of climbing in one of Spain's most barren and hot lands. Though the Almería southeast, the land used in Client Eastwood's Spaghetti Westerns, the Vuelta will cover 188km to the Alto de Velefique. The exposed roads climb up and down all day, all the time you can see the peaks ahead, but the draggy roads will zap riders' morale if not their legs. It may not be so much of a battle for victory but one of elimination heading towards the first rest day.

Stage 14

The Saturday at the end of the second week features one of those typical Vuelta a España goat-path climbs and plenty of room for an ambush. Starting the last loop, the riders ascend Collado de Ballesteros 60km out, a 3km cement path of 15 to 20% gradients. From there, anyone with the legs could potentially trap the race leader before the final climb heading the other way up the the 14.5km Pico Villuercas.

Stage 18

This is the last big day for the climbers to make a difference before the time trial finish and also a day when many riders will be running low on energy, especially since they just raced the Lagos de Covadonga stage 24 hours before. This Gamoniteiru climb is a beast, on the same range as the famous Angliru climb. The Gamoniteiru does not hit the same high percentages, but never-before-used road is tough because it constantly rises at 15 to 17% for the entirety of the 14 kilometers.

Stage 21

Whoever has survived this far into the race to still be in the classification battle will need to switch from their mountain riding position to a long-stretch time trial one. Stage 21 covers 33.7km to finish on Spain's western edge in Santiago de Compostela.

The Vuelta moved away from its traditional sprint finish in Madrid to stay up north and end in Galicia where many pilgrims end their journeys. It's odd to think that a race so known for its climbs could be shaped so much by this individual, flat, timed test. Given some of the minimal time differences in recent mountain stages, this could be a cliff-hanger Vuelta with the time trial having the last laugh.