Power to Weight

‘Power-to-weight ratio’ – or watts/ kg

What is it?

Put simply as a formula:

Power (watts) ÷ Mass (kg)

Why does this matter and how does it rlate to a spin class?

Power-to-weight ratio matters because it’s a good predictor of power, strength, fitness and overall cycling performance.

Take the example of average power output over a 45 minute class

The diesel – strong guy in the back corner of the class who enjoys 70 CAD/RPM all session – weighing in at 110 kgs – averages 290 watts over the length of the class.

The smaller, competitive female rider sitting comfortably at 90 CAD/RPM all session – averaging 205 watts over the same session weighing in at 67 kgs

All riding elements are the same – indoor, same bike, same program, same instructor and music – so let’s do the math.

The Diesel: 290/110 = 2.64 watts per Kg

Competitive female: 205 / 67 = 3.04 watt per Kg

On a group leaderboard – looking at overall energy production and av power – without question the diesel will top the board

However, when the switch is flicked – the diesel comes down the board, with the female rider topping the session

Both riders see their performance over time – but top the leaderboard in their own right- and both feel a sense of achievement!

This is exactly how it plays out in a cycle collective indoor cycling class!

So – take these riders and put them on an outside ride

Put simply simply:

Flat road: The diesel will get to the end of the road, faster ( note – a higher CAD would help his efficiency)

Hill climb: The competitive female will sail passed the diesel and be sipping a latte before he comes over the top of the last ascent

So – what choices do you have to improve your power to weight ratio;

  • Increase your power output while keeping your weight constant
  • Keep your power output constant while decreasing your weight
  • Increase your power output while also decreasing your weight.

Keep reading subsequent blogs to find out how.