While many Zwifters consider fans to be an essential part of their setup, we still hear from some who experience discomfort as they train without adequate cooling. Here’s a quick post to explain precisely why a fan is essential when training inside, and how to best use one.
Is it Hot In Here?
Our bodies operate at around 25% efficiency when converting fuel to pedal turns. That means each watt put into the pedals generates 3 watts of heat. Riding at 200 watts? That means you are generating 600 watts of internal heat. Wow!
When riding outside, that extra heat may be barely noticeable since your body receives a dramatic amount of cooling as the wind swirls around. The faster you move, the more air movement you create: and that’s a good thing, because you’re probably working harder as well.
As your body warms up you’ll begin to sweat, which further increases the cooling effect of the surrounding air as it evaporates.
But what happens indoors? If you don’t have air moving over your body, a layer of overheated air will form within inches of your skin, making cooling even more difficult. Then as you begin to sweat, the lack of air movement will mean minimal evaporative cooling as well.
This increased warmth can be more than just uncomfortable--it may significantly reduce the wattage you can hold.
Overheating Kills Performance
While being “warmed up” is important before hard efforts, overheating is another thing entirely. Excessive sweating and high internal temperatures can dramatically reduce your performance.
According to author and coach Hunter Allen, “Overheating can easily cause a reduction in indoor power by 20 to 30 watts alone...” (from Adjusting Your Functional Threshold Power for Indoor Riding)
Quick Cooling Tips
Fortunately, making your indoor experience a cooler one is easy in most cases. Adding any fan to your setup will make a dramatic difference, and adding more (or better) fans will help even more.
- Use two fans: if a single fan isn’t doing the job, add another! Many Zwifters place fans on the floor to their right and left.
- Get remote control: use a remote-controlled fan or a wifi-connected power strip to allow easy cooling adjustment without getting off the bike.
- Aim at your center of mass: the best place to aim your fan is at your chest. You’ll want air movement on your arms, legs, and face, but moving air off your core is most important.
- Room temperature: keep in mind that air temperature affects cooling as well. While you may only need a bit of air movement on a cold winter morning, you may need two strong fans at full power on a warm summer day.
Looking for a premium fan? Check out the Wahoo Headwind, which can adjust its speed automatically based on your heart rate or trainer speed. It replicates outdoor wind speeds topping out at over 30 mph!