Bike Calculator iPhone/iPod/iPad App

This is the genuine article! And free (ad-supported). It combines the functionality of the SPEED and POWER calculators on this site. Both US and metric units. It includes some new features, too.

Slick! Snazzy! Easy to use. Powerful. Designed by a cyclist who is also an engineer and a photographer - it works great and looks great. Runs on all

Get it here.

Discussion on our FaceBook page. Be sure you provide me with your suggestions and feedback.

Frequently asked questions:

Why is there just one "Main Control", and what does it really do?

Unlike the online calculators, speed and power are updated continuously, so you only need one control. Internally, it adjusts power.

Does the calories number include metabolic calories?

No, just those corresponding to your effort. It is calculated on the basis of watt-hours divided by an estimate of the food-to-mechanical energy efficiency, 25%. This is probably close to what you need to eat for recovery. For losing weight, it may underestimate weight loss, since the overall efficiency of converting food to fat and then to glucose is not 100%. Perhaps I'll add an option for these two situations.

I'm not sure about the predictions for the different surfaces - are they accurate?

Probably not for the softer surfaces - I've not found any data. Even if I had any data, anything other than a hard, dry surface will be variable. By the way, "stone" means the mix of sand and finer crushed stone usually called "stone dust", often used for paving bike trails.

Where should I set the controls on the "More" Settings window?

Leave them in their defaults (95%, 1.00, 1.00) unless you think you have enough data to adjust them. Adjust the rolling resistance slider to correct for low-speed error; adjust the aero slider for high-speed error. I've never seen any data for the myriad sources of mechanical friction loss in a bike's drivetrain, so your guess is as good as mine for transmission efficiency.

Does the calculator adjust the aerodynamic resistance for different weights? Isn't surface area affected?

Version 1.0 does not take weight into account when providing the frontal surface areas for various positions. Maybe in the next version.

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SPEED from Power, Metric units
SPEED from Power, US units

SPEED from Power, all numeric,

POWER from Speed, Metric units
POWER from Speed, US units

Six segments, Power-Metric
Six segments, Power-US

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