Mountain stages are all about attacking and gaining time over rivals. For riders with slight builds, this is the preferred territory for building race-winning gaps because they get the biggest bang for their buck when they attack. Riders like Andy Schleck and Alberto Contador have very high power-to-weight ratios, meaning they can generate a lot of power compared to the mass they have to carry uphill. Expressed as watts-per-kilogram, riders with high power-to-weight ratios wait until the steepest parts of climbs to accelerate because their heavier rivals - who might have the power to chase them down on flat roads - struggle to match their accelerations. But the problem is, as we're seeing in this year's Tour de France, that getting away from each other in the mountains comes down to more than the ability to accelerate quickly.
Attacking requires a huge amount of energy. Riders have to produce a tremendous peak wattage -Sergio Paulinho hit 1097 watts while responding to an attack from Mario Aerts in Stage 10 - while initiating or responding to attacks. The further we get into the Tour de France, and even the further you get into individual stages, the peak wattages for attacks start to decline because everyone is tired. Even so, each, sharp acceleration is a major effort that produces a lot of lactate in the muscles. As the riders continue up the ascent, that lactate gets re-incorporated into the normal aerobic energy-production pathways in the muscles. But each effort that pushes an athlete far over lactate threshold hastens the onset of exhaustion. As a result, riders have only a handful of truly effective attacks in their legs on any given day.
Likewise, the sudden increase in speed during a climbing attack is dramatic, but short lived. The attack is meant to snap a rival off your wheel and quickly establish a 10, 20, or 50-meter gap. After about a minute - or sometimes less - the speed must come down to a level that is more sustainable. From that point the gap may continue to grow, but typically not as rapidly as before. It's at this point that an attack that looked promising starts to get reeled back in.
Bike racers of all kinds use the knowledge that explosive climbers have a limited number of strong attacks in their daily arsenal, and that the speed will return to something more manageable soon after their attack is initiated. This helps pros determine how they will ride in the mountains. Riders like Levi Leipheimer don't like the sudden accelerations and have to rely on the fact that the attacking riders will settle into a manageable speed again. Sometimes this works in his favor and he can ride himself back into the leading group by maintaining a fast and steadier pace while the others surge and recover. He doesn't have much of a choice, though, because riders who don't have physiology for repeated sharp accelerations will ride themselves right off the back of the group if they try to respond to the tactics employed by riders with different talents. Today Levi rode well, but a suicidal acceleration from Alexander Vinkourov at the head of the contenders' group split him off the back, and the subsequent attacks from Alberto Contador, Denis Menchov, and Sammy Sanchez meant the pace never settled down enough for him to regain contact.
People keep asking me why Andy Shleck and Alberto Contador don't just continue to attack each other until someone cracks. In a way, they are, but it's happening over a number of days. They can't keep attacking each other all the way up a single climb because they run out of power. A few days ago, after the stage that covered the Col de Madeleine, Schleck told reporters that if he'd attacked one more time he would have dropped himself, meaning he would have cracked and been unable to follow Contador to the summit. As a cyclist, you have to learn where your limits are. For sure, winning the Tour de France means pushing past those limits, but you may only have the power to dig that deep once in the whole race. Over a period of days, the cumulative impact of the attacks Schleck and Contador are throwing at each other will eventually tip the advantage to one rider or the other. And it's at that instant, the moment when your rival can't respond to an attack, that you need to pull out that once-in-a-bike-race or even once-in-a-lifetime effort to seize on the opportunity.
Chris Carmichael is Founder and CEO of Carmichael Training Systems and coach to Lance Armstrong. In 2010, CTS is celebrating its 10th Anniversary of being the premier destination for coaching, camps, and performance testing. For information on what CTS can do for your performance, visit www.trainright.com, call 866-355-0645, or find us on Facebook at www.facebook.com/carmichaeltrainingsystems.