This year's USA Pro Cycling Challenge covers 617.5 total miles and includes some of Colorado's most scenic roads and highest mountain passes. But of that total distance, only some of those miles will decide the final outcome of the race.

There's a caveat to that statement, of course, since cycling is a famously unpredictable sport. A top rider can see his chances ruined by crashes, exhaustion and poor team strategy, and these catastrophes can occur at any point along the journey. 

Stage races such as the USA Pro Cycling Challenge are often decided by minutes or even seconds. The top riders search out sections of road where they can create time gaps over their rivals. Traditionally, riders target two stages to attack: individual time trials and stages that feature a major climb close to the finish line.

This year's route includes one individual time trial and three mountainous stages that could decide who wins, and who loses. Below, we break down exactly why these stretches of road will decide who wins the 2015 USA Pro Cycling Challenge.

Loveland Pass to Arapahoe Basin (Stage 2)
History: This section is sure to see attacks and aggression because it is the only true uphill finish of the 2015 race. This is the first time that the USA Pro Cycling Challenge tackles Loveland Pass, which was regularly used by the old Coors Classic bicycle race in the 1980's.
Why it could be decisive: The final climb to Arapahoe Basin (10,789 feet) along U.S. Highway 6 starts in Dillon, Colorado, which sits at 9,087 feet. The initial climb is gradual to Keystone Ski Resort, but then the road kicks upward. At just 4.7 miles, the final pitch isn't long, but the steep 6% gradient will definitely hurt.
What to look for: Since the stage comes early in the race, riders will hit Loveland pass with relatively fresh legs. Will any riders be strong enough to attack and stay away to the finish line

? If so, the entire race could be decided by this first test of strength. 

Independence Pass into Aspen (Stage 3)
History: Independence Pass is a monster 37-mile stretch of road that has become a regular attraction at the USA Pro Cycling Challenge. In 2012, the pass saw perhaps the most dramatic stage in the race's history, as Tom Danielson held off a charging peloton on the descent to win the 3rd stage by just a few seconds into Aspen.
Why it could be decisive: This year, the peloton climbs the eastern side of the pass from Twin Lakes, before dropping down to the finish line in Aspen. The eastern approach climbs gradually for about 12 miles, before the grade kicks up above 6% to the top. Much of this steep section is at or above 10,000 feet, which means riders who are not accustomed to the altitude will likely fall off the pace. Huge gaps could occur between groups by the time they crest the summit. The stage's decisive feature, however, could be the 20-mile descent into Aspen. Daredevil riders looking to push the limit could open up gaps as the road winds its way down the valley.
What to look for: If any top riders are dropped on the climb, their hopes for the overall are probably finished. If a late-day rainstorm soaks the descent, riders could approach it more conservatively, which could enable a daredevil to eek out a win.

Moonstone Road into Breckenridge (Stage 4)
History: The second stage of the 2013 USA Pro Challenge produced an exciting finish, as BMC's Mattias Frank attacked up Moonstone Road to claim the victory and Tejay Van Garderen of BMC surprised Tom Danielson of Garmin to steal nearly 20 seconds. That year the stage also included Hoosier Pass before the drop into Breckenridge.
Why it could be decisive: Riders will tackle this stretch of road after climbing both Independence and Hoosier passes, and their legs will be aching. While Moonstone Road is not long, it is painfully steep. A rider who can muscles his way to the top could open a sizable gap on his rivals.
What to watch for: This punchy climb hurts. If a rider is lagging behind on the sprint up Moonstone, his hopes for the overall are likely over.

Breckenridge Individual Time Trial
History: Each year the USA Pro Cycling Challenge features an individual time trial, and each year the stage helps determine the final standings. This year the race debuts a new time trial course in downtown Breckenridge.
Why it could be decisive: In an individual time trial, there's no peloton to create a draft. Instead, riders tackle the course solo, and race against the clock to try and score the best time. Time trials always produce time gaps.
What to watch for: At 8.5 miles in length, the course is not terribly long. But since the riders are going full gas, they will definitely create gaps.