If you’ve been riding in our CompuTrainer Studio this winter or if you ride with your own power meter, you’re at least somewhat familiar, if not intimately acquainted, with the term power-to-weight ratio.
Power-to-weight ratio is the “great equalizer” in cycling. It’s how cyclists can be compared to one another and how you can measure your own progress over time. The ratio is an expression of watts/kg. Power, in watts, is your functional threshold power, FTP, or the amount of power you can sustain for an hour. (If you’re unsure of your FTP, call us to schedule a 20-minute time trial in our CompuTrainer Studio.) Weight, in kilograms, is your weight plus the weight of your bike.
To increase your power-to-weight ratio, you can either make that top number larger or the bottom number lower.
To increase that top number, to increase power output, is the goal of many cyclists. It’s the key to getting faster. It’s what we’ve been working on in our CompuTrainer Studio all winter long. With proper training, including focus cycling sessions, power can be improved to an extent. The rest, however, comes from decreasing the bottom number of the ratio.
As you noticed, there are two variables that make up that bottom number: your weight and your bike’s weight. This is why racers, enthusiasts and “weight weenies” are always searching for the newest and lightest materials for their bikes and components. As you can imagine, lowering your bike’s weight is faster and easier than addressing the two other variables in the power-to-weight ratio.
In fact, this is why we at Higher Gear are always talking about upgrading wheelsets. The more your wheels weigh – especially the weight on the outside of the wheels (the rims, tubes and tires) – the more energy it takes to get your wheels moving. But the weight from wheels is really a factor during acceleration. What about cycling at a steady speed or climbing a hill? That’s where total mass – and aerodynamics – come in to play.
So, what about the second of the two variables of that bottom number, the one that a trip to the bike shop can’t fix?
The last variable, then, is the cyclist’s weight. Finding your ideal weight is key. As is obvious from the equation, a low(er) weight is ideal. A low weight means less weight to pull on the bike and a smaller profile makes for better aerodynamics. But your weight shouldn’t be so low as to either put yourself at risk with a body fat that is too low or to lose too much muscle that your power number suffers.
Ideally, you’re at a healthy weight with lean muscle and minimal (but essential) fat. The lower your weight, the less weight you have to carry – and pull – on the bike. It’s why the smaller, lighter guys make better climbers in contrast with the guys with the big powerful legs who are better sprinters. (Think Schleck brothers versus Mark Cavendish: poor Cavendish trying to get the weight of his legs over a mountain! And those Schleck brothers just aren’t built for sprint stages.)
(If you need a visual, check out the image of track cyclist Robert Forstemann comparing his thighs with fellow German Andre Greipel. And keep in mind, Greipel is a sprinter, but he also needs to be able to meet the demands of the other stage profiles in races, whereas Forstemann only needs power for the track.)
The elusive “race weight” is what every endurance athlete seeks. It’s the point where weight is lowest without losing valuable muscle needed for power where it’s needed.
Most of us who are not elite athletes have extra pounds we can afford to lose. So what’s the best way to go about that? Stay tuned for Part 2 of Weighing in on Cycling Weight.
For more info about cycling weight, check out Mike Schulz’ article on Training Peaks – Parts 1 and 2.
For those geeking out on power, on Training Peaks you can also find Andrew Coggins’ Power Profiling for cyclists in different disciplines.
Years spent working in health clubs, our resident fitness guru, Joy Sherrick, shares with us the wisdom of her years of experience working with people to meet their fitness goals.