Why is Winter Cycling Harder Than Summer Riding? It's Not What You Think.

Sure, cycling in winter requires a bit more commitment, fortitude, and gear than the balmy days of summer. But turns out that cold-weather riding also requires more effort, even if you're riding the same bike on the same roads you do in summer.

Why? Physics are working against you. Cold air is denser than warm air, which increases the amount of drag on you and your bike—and thus increases how hard you have to work to maintain the same speed. How much denser? A recent post by bike guru Lennard Zinn provides the answer.

You can read all the gory scientific details in Zinn's post, but it comes down to this. At 25 degrees Fahrenheit, air is 10 percent denser than at 75 degrees. Since drag is proportional to density, that translates into a 10 percent increase in drag as well.

Crunching the numbers, that increase in drag ultimately translates into a roughly three percent decline in performance. As in, it would take three percent longer to travel a given distance for the same amount of effort in 25-degree vs. 75-degree conditions.

Other factors can also increase the amount of effort required for winter cycling. Extra layers that increase your surface area create more resistance. As the blood vessels in your extremities constrict in response to the cold, your heart has to work harder to pump blood through them, which also translates into a more rapid rate of fatigue. And, of course, if you're riding on studded tires, the extra friction and rolling resistance requires significantly more effort.

All that being said, my personal takeaway as a regular winter bike commuter is this: Awesome! I'll happily take the bonus exercise, which helps increase overall fitness and ensures that come the warm weather I'll be riding faster and fitter than ever before.

Ride on!

Learn more about cold-weather cycling:
Ride On! How to Bike Through Winter (2009)
Winter Cycling: How to Keep Your Head and Ears Warm (2012)
Best Biking Balaclava? Try the Pearl Izumi Barrier (2013)
The Warmest Winter Cycling Shoes? The Wölvhammer Boot from 45North (2012)
Studded Bike Tires for Winter, Part 1 (2011)
Studded Bike Tires for Winter, Part II (2011)
Winter Cycling: My Clothing System (2010)
Winter Biking: Keeping Your Hands Warm--Are Bike Pogies the Answer? (2009)

Equipped” is an AMC Outdoors blog, written by Matt Heid.

Photo: Flickr Commons; Team Traveller

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