We've had numerous questions regarding Peloton's data relating to speed & distance, so we've provided some high level thoughts regarding the relationship between output, speed & distance.

### What is output?

Output (measured in wattage) is the power you produce with your legs to get your pedals turning.

On a spinning bike, output is simply how much effort is required to turn the pedals at a specific resistance. In the ‘real’ world, output is calculated in the same way; the effort required to turn the pedals to overcome opposing resisting force to move your bicycle forward.

### Real world resistance factors

In the real world, to move your bicycle forward (i.e. speed) you need to overcome four main resisting forces:

Resisting force due gradient – it is easier to cycle downhill than uphill.

Resisting force due weight - heavier people are required to exert more effort than lighter people.

Rolling resistance force – the friction between your tyres and the road, which will vary depending on your tyre type and road surface.

Aerodynamic drag – the force of air resistance as your speed increases. Different cycling positions can either increase or decrease aerodynamic drag.

The above four forces are relatively complicated to calculate and is potentially too much detail for the purposes of this article. All you need to appreciate is this:

Your speed will depend on how much effort you are exerting at any given time to overcome the opposing forces related to you and your bicycle; (1) your weight, (2) the gradient of the road, (3) your tyre type / road surface and (4) your cycling position impacting your aerodynamic drag.

For more detail on these metrics and opposing forces, see the OmniCalculator.

### How does Peloton calculate speed?

Referring to the above points we have made regarding you and your bike, according to our testing of Peloton’s speed calculation, we believe:

Peloton assumes a constant weight across all users – i.e. there is no difference in speed if you weigh 150lbs or 250lbs. Our estimate is that there is generic weight of 190lbs applied to all Peloton users when calculating speed.

The gradient of the road never changes – i.e. even though you may increase or decrease resistance on your spinning bike to simulate an uphill or downhill, the speed calculation always assumes you are on a flat road. To see this in action on your Peloton bike, next time you increase your resistance, take note of the immediate increase in speed - this is a direct result of gradient remaining flat in this calculation, and thus if output is increased, the only 'balance to the equation' will be an increase to speed.

To avoid confusing the matter, we will exclude our analysis on the (3) assumed tyre type / road surface and (4) cycling position impacting aerodynamic drag

### Does speed really matter on a spinning bike?

Most probably not – output is the most important factor on your spinning bike and should be used as the true measure of how your fitness improves.

However, as the Peloton community continues to look for ‘more’ out of their spinning bikes, we see this community taking part in ‘distance based’ events, i.e. a 50 mile or 100 mile goal ride, and so we are receiving more and more queries about the accuracy of speed and therefore distances travelled when compared to the real world.

### A worked example:

To put the above Peloton calculations into context, let’s compare 3 different road cyclists who weigh 150lbs, 200lbs and 250lbs respectively, all of them are cycling up a 3% gradient hill exerting 200 watts of output for 30 minutes.

150lbs cyclist: speed of 14mph and will travel 7 miles.

200lbs cyclist: speed of 12mph and will travel 6 miles.

250lbs cyclist: speed of 10mph and will travel 5 miles.

Alternatively, how much output (in watts) is required by each cyclist to each maintain the same speed (14mph) and thus the same distance over a 30-minute period up a 3% gradient hill:

150lbs cyclist: 200 watts

200lbs cyclist: 250 watts

250lbs cyclist: 300 watts

Long story short, Peloton’s speed calculation and therefore distance (given speed and distance are directly correlated) are not a true representation of you and your individual circumstances when compared to the ‘real’ world.

How important is speed & distance to you on your spinning bike setup ? Let us know in the comments below.

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