Any race, be it a three-week grand tour or twilight criterium, can be won or lost in an instant. One bad crash, a bonk, or even something as random as an insect bite can end weeks and months of preparation.
Bike racers, however, are a durable breed, and the world's top races often come down to just a handful of decisive moments. The 2012 Giro d'Italia was chock full of them, with Ryder Hesjedal (Garmin-Sharp) and Joaquim Rodriguez (Katusha) battling all the way to the final finish line in Milan, the former saving his race from the clutches of Thomas De Gendt (Vacansoleil-DCM) on the slopes of the Passo dello Stelvio.
The 96th Giro d'Italia course is front-loaded to hold suspense to the final weekend, but the three-week route from Naples to Brescia is loaded with surprises, potential traps, and intrigue the entire way.
Hesjedal, Vincenzo Nibali (Astana), and Bradley Wiggins (Sky) line up Saturday as the top favorites, each with their respective game plan for how to tackle the Giro. Wiggins will count on his time trialing prowess while Nibali hopes to explode the race in the steep climbs. Hesjedal hopes his ever-steady consistency keeps him in the battle to the end.
This year's Giro course packs most of the decisive stages into the final half, with the last week delivering a brutal run from the Col du Galibier to Tre Cime. Early time trials and some deceiving stages in the first half will certainly play a factor in who eventually claims the pink jersey May 26 in Brescia.
These are the key moments -- the kilometers in which the 2013 Giro will likely be won or, more likely, lost.
1. Time trial advantage
Despite being thick on climbs and short on time trials, the most decisive moment in this year's Giro could well come at the end of the first week. Some 55 kilometers of mostly flat roads could well be the pivotal point of the 3,200km march from Naples to Brescia. The individual time trial from Gabicce Mare to Saltara favors Wiggins so much that the stage could prove a race-breaker.
Comparing former time trials in other races is akin to comparing apples to oranges, but there's no doubt that Wiggins holds a huge advantage against the clock. In last year's Tour de France, Wiggins took 2:07 out of Nibali in 41.5km and 3:38 in 52km in the two time trials. Hesjedal didn't make it to the Tour's time trials last year, but he ceded 5:26 to Wiggins over 44km in last year's Olympic Games.
Those numbers are deceiving because every race is different, of course. Nibali and Hesjedal have each improved against the clock while Wiggins said he's worked more on his climbing at the expense of his time trialing. Wiggins hasn't raced a major TT this season, so it's difficult to gauge exactly where he is.
Sky is clearly hoping Wiggins can take important gains against his top GC rivals and carry the pink jersey into the final week with a healthy head start. As Wiggins said himself, it won't matter if he takes five minutes in the time trial if he loses six minutes over the Stelvio.
2. Tre Cime ramps
The 96th Giro could very well come down to the final charge up the final climb the race's final day in the mountains. The 203km 20th stage from Silandro to the Tre Cime summit in the Dolomites has all the makings of a classic.
This old-school Giro grinder features five major climbs, with the Tre Cime summit hitting 12 percent over the final 3km. This stage is so hard and so demanding that nothing will be secured until the pink jersey is across the line. With time bonuses waiting at the finish line, the GC could come down to a nail-biting finale in the penultimate stage.
Last year's down-to-the-wire battle revealed how tight the Giro can be. This year's even deeper field should see a seesaw battle to the end.
3. Galibier giant-killer
With the exception of the penultimate stage to Tre Cime, the Giro has packed most of its decisive climbing into shorter, more explosive packages. Take, for example, the 149km 15th stage from Cesana Torinese to Col du Galibier. Two monster climbs -- Mont Cenis and the Col du Télégraphe -- are packed into the stage before hitting the giant of the Alps at the Galibier.
The GC contenders will need to walk the tightrope to manage these shorter, highly unpredictable stages. Riders will be keen to risk all and go on the attack early, knowing that the cumulative distances in most of the mountain stages are reduced by up to 30 percent compared to the traditional model of 200km-plus stages.
Recall the mayhem of the 2011 Tour de France's brief romp over the Télégraphe and Galibier to Alpe d'Huez? It is coming to the Giro and could even be amplified, as many things are here.
4. Hill-top mayhem
Although this year's Giro features fewer short, intense hilltop finales than usual, these finishes can lead to important time differences. In last year's wild fight between Hesjedal and Rodriguez, the punchy "Purito" used the short, steep finales to turn the screws on Hesjedal.
This year, the first half of the race features a handful of traps that could prove tricky for the likes of Wiggins, who prefers the longer, steadier climbs of the Alps. One example comes in the first week with stage 4, a 246km run to the Giro's southernmost point. The stage features one of these "Giro traps." The pack will hit the second-category Croce Ferrata before a technical, twisting 5km descent to the finish line, ideal for deft descenders such as Nibali and Sánchez.
5. TT flier
Climbing time trials rarely make a huge difference between GC favorites, unless someone is absolutely flying. The 20.6km course up the Polsa climb in stage 18 features a steady, two-part climb that could see someone with spectacular legs charge clear of the pack.
The climb opens with a steady, 9.5km section with a constant grade of about six percent. Following about five kilometers of flatter terrain, the course kicks up again for 6km, though slightly steeper than the opening section, with one ramp as steep as 10 percent. Anyone who can hold the speed could make some important gains ahead of the final round at Tre Cime.