What is a realistic way to compare riders of different weights and genders? How can one person complete a course in record time with numbers that would barely propel another person across the course?
Speed is affected by a number of factors mainly power, weight and aerodynamics, which all come into play to determine how fast you’ll finish a course.
Comparing your power file with a friend’s may leave you wondering why it took him or her less work, literally, to complete the same course you did. Power is the component of speed generation that many of us focus on because we can control it. Learning to ride stronger is the goal of any competitive rider, and increasing your power output, for example averaging 225 watts over an Olympic bike leg instead of 200 watts will make you go faster.
There are two different weights to consider: that of you, the rider, and that of your actual bike (and stuff on your bike).
Let’s consider two riders: A rider who weighs 73 Kilos and manages 225 watts instead of 200 watts will be faster, but a 55 Kilo female putting out 225 watts will be faster still as it simply does not take as much energy to move so much less weight!
One common method of comparing cyclists to one another is looking at power-to-weight ratio for different time periods. Using Dr. Andrew Coggan’s chart you can see how you measure up and, more importantly, track improvement.
If you have a power meter and use software such as Training Peaks, you already have a power profile chart in progress that will keep record of your best performances.
The second portion of the weight factor is what is on your bike. While riders often stress about a few grams of difference between components, think about the much greater weight factors of an extra bottle or two.
The third factor to produce speed is overcoming drag: air density, wind speed and that of your body and bicycle. So our 73kg male and 55kg female both producing 225 watts will see their times as much more similar the flatter the course profile.
Measuring your drag is a difficult task without a wind tunnel or controlled conditions, but you can start by getting a good bike fit from an experienced fitter. Remember that there’s an important balance between aerodynamics and comfort if your bike fit is too aggressive or focused on the fastest position possible, it won’t be worth it if you’re never comfortable enough to ride in the aerobars.
There are a few items that will have an impact on your aerodynamics: an aero helmet and deeper-rimmed wheels on the more expensive side and, on a smaller scale, a tri kit that fits snug and a hydration system that is designed to hide from the wind.
Best chance for improvement
Heavier cyclists will be at less of a disadvantage on a flat course, especially if they have a good position. Lightweights with a good power-to-weight ratio will be at an advantage on a hillier course, while a cyclist of any size and weight with a great position (and an ability to hold it) will be able to maximise their performance on any type of course.
So which angle should you focus on for optimal performance—weight, power or an aerodynamic position? If you know you’re lacking on the training front, it may be relatively “easy” for you to increase your fitness and power simply by training more. If you know you’re carrying some extra pounds, then you may want to focus on a faster power-to-weight ratio.
And if you’re the type of triathlete who rides with five bottles, two bento boxes and spare tires strapped to the frame while sitting up, it may be easy for you to pick up time by improving your aerodynamics. Ideally, you will be able to work from all angles for optimal performance.
Predicting the “win”
Let’s say your goal is to get your functional threshold power (FTP) from 3.0 to 3.5 watts per kilogram, a competitive amateur goal. Here is a simple example that illustrates the effect of weight loss:
Man: 80 kg x 3.0 watts per kg = 240 watts at threshold
Woman: 61 kg x 3.0 watts per kg = 183 watts at threshold
Power gains needed to reach 3.5 watts per kg
Man: 80 kg x 3.5 = 280 watts at threshold
Woman: 61 x 3.5 = 215 watts at threshold
You can see that the male rider will have to increase his FTP by 40 watts to reach 3.5 watts per kg while the female rider must increase hers by a whopping 32 watts.
Unless you’ve only been cycling for a short time, or are coming back from a long hiatus, those are some tough gains.
Now let’s take a look at the impact of a 4.5kg weight loss for each rider, assuming they can successfully keep the same power output.
Impact of 4.5kg weight loss
Man: 75 kg x 3.5 = 262 watts at threshold
Woman: 56.8 kg x 3.5 = 198.8 watts at threshold
By losing only 4.5kg, that decreases the gains needed by our male rider to 22 watts and our female rider to only 16 watts, less than half the increase needed if they both were 4.5kg.
Depending on your starting weight and what you can comfortably lose while keeping your power, a combo approach is the best bet.
Note: We did not try to calculate the effect of improved aerodynamics on the performance of our two riders.