Rolling Resistance of Bike Tires
Ever wonder how much of your pedaling energy goes into the tires of your bike? If you're a racer, you probably want the fastest set-up, so looking for the fastest tire may make sense. Or maybe you're wondering why those roadies whir pass you on your mountain bike. They can't be that much stronger than you! Or can they?
Road Tire Test
Here are the results of tests on road tires. They show how many grams of force must be applied to overcome the resistance of the rubber in the tire. Using your gearing and crank length, you can determine how much force you must put into the pedal to produce this force at the tire. To determine power requirement at a given speed, simply multiply the resistance force by the speed. Click on the images below for a larger view:
Variety of road tires
Avocet and Specialized
Here is a discussion of these bike tour rolling resistance tests from Jobst Brandt, who provided the data.
More Road Tire Tests
Here are the results of another road tire rolling resistance test, from the testing lab at Continental in Germany (click the image to see the source article):
Note that the power difference between the best and the worst tire is over 20 watts, so switching tires can feel like gaining 20 watts of power. And that's a 18.6 mph. Higher speeds will reap even more power savings.
Mountain Bike (26") Tire Test
Note: These mountain bike tire tests were performed with a 30kg load, while the road tire tests were performed with a 50kg load. Since rolling resistance increases with load (perhaps linearly?), if you want to compare the numbers in the two charts, multiply the mountain bike numbers by 1.67. Click on the image below for a larger view:
Terry's Bike Information Page
Terry's page on California Bicycle Touring