Using a power-to-weight ratio is an easy and effective way to determine the amount of watts to target during various efforts. It is a very simple approach that is easy for instructors to use in classes where bikes with power meters are available. With any simple approach, there will be factors to consider for those who desire to be the exception.
When riding a bike outdoors, our friend gravity gets to flex some muscle. Simply put, because of gravity’s effect, heavier riders must move more mass (weight) to propel the bike up the road, or literally, up a hill. A heavier rider must produce more power in order to climb a hill at the same speed as a lighter rider. Because of this, a person generating more power (watts) than another may not be stronger or faster when the rubber meets the road.
Besides relentlessly pressing your sore glutes into the ever-torturous seat, gravity does not play the same role indoors. On an indoor bike, riders are neither physically propelling their body weight up the road, nor are they carrying their body weight up a hill. However, generally speaking, a rider with more mass can often produce more power than a rider with less mass. Hence, a power-to-weight ratio still applies.
Power CTW: Power-to-Weight
What is you have someone who weighs quite a bit – this seems like it would be nearly impossible for them to reach. Am I missing something?
Great articles. Our Y has had Keisers for about 3 years. With your wonderful articles and profiles I have “stepped up my classes”. However, I myself and my students have not been able to double our watts to weight. Is there a technique that I’ve missed?
Thanks for the the information.
I really appreciate this simple language and layout. Knowing my audience, which is a diverse group of predominantly indoor, group fitness enthusiasts, this feels like a perfect fit to getting them started on understanding their individual power potential so much better! We have Keiser bikes in our studio (YMCA) and I sometimes feel the numbers overwhelm them, especially newer riders. With this layout and the options for both newer riders and the seasoned roadies, I feel more confident delivering a ride they can each feel successful with and set goals by.
As a result of Stephen’s excellent comment, I’ve updated the article to include both pounds and kilograms. Only the section entitled “Power CTW: Power-to-Weight” was amended.
Thanks for the article Tom.
I don’t see in this article, nor in the previous two, a mention of how to calculate Power CTW (Power-to-Weight). You mention Power CTW in your first article…
So my assumption is, since you are based in the US, that your are using pounds divided into the number watts. Just clarifying. Not everyone measures mass in pounds…some may still use ‘stone’ 🙂
Great comment Stephen. I have not calculated power for stones yet. However, for kg, here is what I recommend:
– < 1 x w/kg = Very Easy - 1 x w/kg - Easy - 2 x w/kg - Moderate - 3 x w/kg - Hard - 4+ x w/kg - Very Hard For the other Power CTW approaches, one is just experimenting with the number of watts per a specific rpm or length of time.