AIn 2013, a lot of ‘Chris Froome Looking At Stems’ photos ‘did the rounds’. So many, in fact, that there is now a website dedicated to the subject with many wondering whether he was actually looking at his power-meter display, rather than a fairly dull cycling component.
In this article we explore:
- What type of power-meters do many professional cyclists use?
- How do power-meters calculate power?
- What information do pro-cyclists want to see from their power meters?
- How might professional cyclists use power meters in training and racing?
Personally, I think it’s very likely that Froome and the other Team Sky riders are taking regular looks at their power meter displays (re-branded Garmins this year) to check their pacing. At times, they may even be taking a sneaky peak at the power output of some of the riders around them! Assuming that Froome is looking at the display clipped to his handlebars, what would he be looking at? Can we learn anything from this to help us go quicker?
During this year’s Tour de France, discussions about power measurement reached fever pitch. It seemed like every man and his dog had an opinion about rider’s ‘watts per kilo’. Many of the comments seemed to be cynical in nature, whether it was an insinuation of doping or criticism of ‘robotic tactics’ governed by SRMs. Whatever the perspective, it’s beyond dispute that the public cycling lexicon has embraced the relatively new world of ‘watts’ and its associated terminology.
It’s all very interesting and potentially confusing. Based on my knowledge of power training and SRM systems, I’m going to provide an overview of what is happening under the skin of an SRM crank, during Chris’ effort and speculate about what data he may be looking at during a Tour de France stage, afterwards in debriefs with coaches and trainers and suggest how we may learn from this to improve our own performance.
In an earlier blog, I wrote briefly about the history of cycling power meters. The crank based SRM system, first brought to public attention by Greg Lemond, has become one of the most popular power measurement systems in the professional peloton, as well as amongst enthusiastic amateurs. First patented in 1987, the SRM uses 4 ‘measuring bridges’ at points where the chainrings join the crank arms. The SRM website has an excellent feature on the design, manufacturing and calibration process. Team Sky are well known aficionados of the SRM system. When Chris Froome pushes down on the pedal, force from his leg is applied to the crank arm. The measuring bridges in the SRM crankset measure this force as torque, with great accuracy. This measure of torque is entered into a calculation and multiplied by ‘angular velocity’. Angular velocity is a measure of the speed of the pedal stroke, derived through the cadence and the length of the cranks. The resultant value (Torque x Angular Velocity) is equal to the power which Chris Froome is producing, measured in watts. The SRM crankset wireless transmits this data to the PCV ‘Power Control’, attached to Froome’s handlebars, which receives an update 4 times every second and displays the information in real time.
During The Race
A cycling power meter is a very accurate biofeedback mechanism. As I mentioned in a piece I wrote for Cyclefit power meters give an objective measure of the physical work being carried out by the rider. Experienced athletes are often able to gauge this effort intrinsically through highly trained proprioceptive skills. However, even for experienced athletes, fatigue and environmental conditions mean that perceived exertion is highly variable, subjective and even completely wrong. There are plenty of examples of riders who have felt great at the beginning of a climb, set an aggressive pace before exploding spectacularly, or simply clung to the group that caught them whilst they rued their wasted effort.
From what I’ve read and heard, it seems highly likely that through extensive pre-race training camps, race simulations and recces, Froome and his team of trainers and coaches have a very accurate idea of what he is capable of and that they have defined this capability in objective terms. Specifically, Froome will likely have a very accurate idea of the wattage he can maintain and the pacing/tactics that he can apply at a given point in the race. For example, Froome’s aggressive changes in pace on Mont Ventoux have been widely reported. However, it’s unlikely that these tactics came out of the blue. Team Sky’s predilection for brutal ‘crisscross’ workouts in training, is well known and provides a interesting perspective on Froome’s Ventoux performance…
During Crisscross training, the athlete carries out a number of prolonged interval efforts. For example, the athlete may begin a workout by riding at a power output that they could maintain, without fatigue for 1-hour. However, rather than riding consistently, every 2 minutes during this hour long effort, the rider would make a 30 second burst at over 120% of their 1-hour power, before returning to 100%. This type of effort forces the athlete to briefly and repeatedly produce more energy through anaerobic metabolism (without oxygen), before returning to predominantly aerobic metabolism. Consequently, the athlete must process lactate whilst maintaining a relatively high effort intensity, which closely mimics the relentless high speed and repeated accelerations that characterise competitive cycling. Through conducting these training sessions prior to competition, the rider and coaches will have an accurate idea of what power can be maintained during the steady-state and burst periods and also how many burst efforts can be made before fatigue occurs.
It was this kind of knowledge of the limits of a rider’s performance (though it was derived rather than measured directly) that allowed Dr. Michele Ferrari, during the 16th stage of the 2000 Tour de France, to advise Lance Armstrong that Marco Pantani should be unable to sustain the effort following his attack on the first climb of the 196km route to Morzine.
Chris Froome’s SRM
So, what would Chris Froome be looking at during these Crisscross type efforts, whether in training or racing? The video footage from the 2013 Tour de France Ventoux stage suggests that Froome was making regular glances down at the SRM’s display. Traditionally, pundits may have suggested he was looking at heart rate. Whilst this can provide a useful indication of physiological load – how hard your body is working to produce the effort – it’s highly variable and affected by many external factors. Today, we know that Froome is likely focussing on his watts. He’ll know exactly what base-line sustainable power he could sustain for the 59 minute climb to the peak of Ventoux. Perhaps more importantly, he also knows what intensity and how many burst efforts,over this base-line, that he could make. For the most part, he’ll be glancing down to confirm that he’s producing that level of power. Once he’s accelerated, he may glance down again to double check he’s hit the power level he’s aiming for in the ‘burst’, before settling down again to resume the previous Critical Power level. Chris Froome’s ascent of Ventoux was essentially a Crisscross effort, something he and the other Team Sky riders have spoken about carrying out many times before in training, particularly on the slopes of Tenerife’s Mount Teide.
You can find out more about training using the ‘Critical Power’ concept, here.
What Can We Learn From Froome Et Al.?
Forgetting the insidious influence of performance enhancing drugs for a moment, we’d all like to believe that somehow people are able to pull super-human efforts out of the bag come race-day thanks to the ‘extra motivation’ of big events, but the reality is often much less romantic. These ‘other-worldly’ performances are increasingly the result of meticulous preparation and analysis, facilitated in part by power measurement systems such as the SRM and the in depth data this provides, both during and following their performance. We can learn much from this approach. In my experience, both in amateur racing and working with professional athletes, the training of many cyclists simply does not reflect the demands of the events they will be riding. I’ve made the same mistakes myself. Hours of riding a 33km.hr, surprisingly enough, made me very good at riding at 33km.hr. I could complete a 180km race without any difficulty, but the races were won and lost during 15 minutes of brutal bike-to-bike combat that my physiology was not prepared for. Similarly, how many riders have spent a winter diligently logging hundreds of miles on their Cycling Weekly chart only to wonder why they’ve been dropped like a stone on their first race of the season?
Specific Training Creates Specific Tools
Specificity is the first principle of training for a reason. There’s no doubt that Chris Froome has been blessed with an incredible genetic advantage and will to win, but he has developed this through training, many trials and simulations, to understand himself extensively, create the tools i.e. the physiological adaptations necessary to compete, allowing him to ‘dose’ his energy expenditure for maximum effect. The Crisscross effort is a great example of how specificity in training and technology may have combined to provide the tools for Froome to escape the lead group, deliver the killer blows to Quintana and win the stage.
Could this have been achieved without a power meter? Maybe. Chris Froome, whilst a prodigious talent, is still a relatively young cyclist. For some cyclists, it takes many years to develop their proprioception – the ability to accurately gauge effort, but as we mentioned earlier, even if this sense is well developed, it’s not fool-proof. Heart rate provided an early means to improve feedback. Whilst using a measure of heart rate can be a helpful during longer efforts, in short crisscross training and race efforts, heart rate can not respond quickly enough.
Lack of proprioception/accurate perceived exertion and poor data from heart rate has a number of impacts:
1. When gathering data during racing, without a power meter, there is no way to quantify, objectively, how big the surges are that characterise competitive cycling.
2. As a consequence, during training, it’s difficult to accurately replicate these efforts to create the adaptations required to achieve them in racing.
3. Without a power meter, it’s almost impossible to determine how these short efforts in training compare to each other as the session progresses – speed and heart rate are too dependent on external factors. Consequently, it’s difficult to know when you’ve done enough to elicit an effective training ‘dose’ i.e. when you’ve done enough, or too many intervals.
Staring At Your Stem
Having a good stare at the power meter on your stem can solve a number of these problems. Recording efforts in competition using power helps you to understand both the objective demands of the event and your strengths and weaknesses when it comes to meeting these demands. For example, if you find you get dropped during short steep climbs, your power data can explain how much power you were producing when you got dropped and help you to estimate how much you needed to stay with the group. A bike based power meter means that you can design a training programme to replicate these efforts and address how to improve them as part of a structured training programme. Power meters provide immediate and objective feedback about the effort your are undertaking, helping you to track effort intensity accurately, to make training more specific and answer the question “just one more interval?” or “call it a day?” with confidence.
If your efforts in training do not reflect the specific demands required by competition, it’s highly unlikely that you’ll be able to ‘pull something out of the bag’ come race day. In cycling, as in many sports, we’re deeply wedded to the idea that competition can provide that special something extra – that when you pin a number on and come up against your biggest rivals in the most important event of the year, something spectacular happens. This story makes great copy for newspapers. I’m not denying that competition elevates performance. However, whilst it doesn’t make for such compelling reading, I’m inclined to believe that the great performances we see in competition are the result of preparation, a structured training programme specific to the demands of the event, carefully planned tapering, tactics and an ever necessary dose of good luck!