Welcome to the oldest and most popular bicycle performance prediction calculator on the web - since 1997. Effortlessly compute speed or power for all important parameters, such as weight, grade, position and tire type. This is actually an "engineering model" that knows the relationships between power, speed, and the three major forces: gravity, wind resistance and rolling resistance.
You can enter your velocity to get your power, or vice versa. Or use the handy slider to change both at the same time (may not work with some browsers). You can choose metric or U.S. units.
You can also enter values for time, energy expenditure, or weight loss - your ride distance will be adjusted to match.
If you have any trouble or have suggestions, let me know: email@example.com. Some of the old calculators are still around - see the "Old Stuff" menu item above. One allows numeric entries for all parameters instead of menu picks. One allows you to enter parameters for five ride segments.
Check out the iPhone version of this calculator.