Benchmark testing
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Benchmark testing
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April 13, 2018
Journey to Ironman Texas with Dr. Chris Tubbs
August 13, 2019
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Improve Your Cycling Using the Power-to-Weight Ratio

triathlon bike gearing

Improve Your Cycling Using the Power-to-Weight Ratio

As cycling has become increasingly data-driven, itʼs now more clear than ever that going fast on the bike isnʼt just about pushing hard on the pedals. To the detriment of those who enjoy a good donut or three, a golden ratio has emerged which is used to significantly improve performance over climbing and time trial efforts. Although the power-to-weight ratio may not be unheard of, few appreciate its implications in taking cycling performance to the next level. Improving your power-to-weight ratio will deliver marked improvement to your best climbing times and fastest time trials, and will leave you with more to give at the end of a long, hard, hilly day. If youʼre wondering about the details of power-to-weight ratio and how to use it to your advantage, read on and wonder no more.

What is the Power-to-Weight Ratio?

Imagine two riders who resemble twins. Their height, weight, and build are the same. Their power output on the bicycle is, strangely enough, also the same. With all things being even, these two riders should perform at the same level on flats and up climbs. Perhaps only circumstantial factors such as positioning and headwind would determine a faster rider between the two over a given route.

Now imagine one of the two riders gains weight – 10 pounds to be exact. During this period of weight gain, our rider also made no improvements to power output, but they also didnʼt get any worse either. They simply maintained what they already had in terms of power.

Now, both riders race each other up their local climb. Nothing has changed for either of them apart from the 10-pound weight gain for rider A. As they hit the climb, rider A finds himself unable to keep rider Bʼs wheel. Rider A gets dropped completely and finishes the climb wondering what happened. At the top of the climb, the two riders compare data and find that rider A was, in fact, producing higher wattage than rider B but was still dropped anyway. What happened? When cycling uphill, absolute power – the amount of power a rider can put out without taking weight into consideration – matters less than the relationship between a riderʼs absolute power and weight.

This relationship is the power-to-weight ratio expressed in the simple watts per kilogram (W/kg) metric. This metric is a direct representation of the amount of power a rider is capable of for each kilogram of body weight. The higher the number, the bigger the capacity for performance in races with hills, climbs, and rolling time trials.[1]

How to Improve Your Power-to-Weight Ratio

Improving your W/kg is a direct and surefire way to see notable differences in your racing abilities. The majority of road races and time trials use a hill or climb to shake racers out and create will divisions amongst the contenders. In theory, riders with higher wattage per kilogram will outperform those with lower metrics. The three ways to go
about improving your W/kg are fairly uncomplicated but take commitment, time, and routine:
Increase fitness/power but maintain current body weight
Maintain fitness/power but lose body weight
Increase fitness/power and lose body weight[2]

Calculating W/kg

Before deciding on a method for improving your power-to-weight ratio, itʼs necessary to first calculate your W/kg. Letʼs make an example out of Bob who is 6 feet tall and weighs 200 pounds. First, we convert Bobʼs weight into kilograms (1 kg = 2.2 lbs). That gives us 97 kilograms. Next, we divide Bobʼs threshold wattage by his weight in kilograms (300w /97kg) giving us 3.1W/kg. Once you have your W/kg calculated, you have an objective measurement by which to gauge your training improvements when finding your balance between power and weight.[3]

Losing Weight

Losing weight is a straightforward way to improve your power-to weight ratio. The only thing to pay attention to here is that you donʼt sacrifice power by losing too much weight. Losing too much weight too quickly will result in a degradation of your performance which is the opposite effect intended.

Letʼs say that Bob is tired of getting dropped in every race with a climb in it. He decides that itʼs high time to lose some kilos. Over the course of a winter spent base training, cutting out junk food, and counting his calories, Bob is able to drop his weight by 30 pounds. At the same time, Bob maintained his threshold power. Now, if we recalculate Bobʼs W/kg (300w / 77kg), we find that heʼs sitting at 3.9 W/kg. This improvement in performance takes Bob into an entirely new bracket of performance that he likely wouldnʼt have been able to achieve by maintaining his old weight and simply trying to improve his threshold power. This explains why pro riders in training for grand tours focus just as hard on losing weight as they do on any other aspect of their performance.

Time Counts

So, youʼve taken one of the three aforementioned routes to improving your power-to-weight ratio. Now you should be faster all the time, right? Well, not quite. The twist is that your W/kg is always in reference to a certain duration. As the duration of an effort increases, your effective W/kg decreases, which shows why weight is also directly tied
to endurance.[4]

When Does the Power-to-Weight Ratio Really Matter?

Your power-to-weight ratio matters more as the road climbs, and less as the road flattens out. But, absolute power does play a big role in helping a rider to overcome headwind regardless of the terrain. This is why races with a punchy and fast uphill finish are often won by riders with more mass than skinny climbers. Even though, in theory, a skinny climber might have a higher W/kg measurement than the stockier one, the stockier rider’s absolute power punches them through the headwind with greater conviction.[5]

1. “Everything You Need to Know About Power-toWeight Ratio.” ↩
2. Thomas, Taylor. “Why You Should Focus on Watts per Kilogram” ↩
3. “Power to Weight Ratio: Watts Per Kilogram
Explained and How to Boost Yours.” ↩
4. Ibid ↩
5. Allen, Hunter. “Power-to-Weight Ratio: Why Itʼs So Important in Cycling.” ↩