Total Power – Measuring Cycling Wheel Performance

In cycling, the power you put into the pedals is measured in watts.  Ideally, each watt is used to move you forward, but in reality, only a portion of those watts are used for that purpose and there are losses along the way. As a cyclist, every watt you haven’t lost counts towards how fast you’re going.

There are four main components that make up the the watts required for you to ride a bike at a specific velocity. The equation below is taken from the Chung Method.

As wheel designers, our goal is to design wheels that will make you faster. If you take a look at the equation above, there are two main areas outside of weight in which we can focus our efforts to achieve this goal; the watts that account for rolling resistance, and the watts that account for air resistance.

At FLO, we measure a wheel’s performance by determining the Total Power, or the number of watts required to roll a wheel. This consists of the watts for rolling resistance + the watts for air resistance. If we’ve done our job properly, this number will be as low as possible. Once we know the Total Power value of a wheel, we can estimate your time savings over common races and distances. Skip to the end of the article if you aren’t concerned with all the details and just want to know your time savings. For those looking for the details, let’s explore each component further.

If we look at the equation for the rolling resistance we see the following:

The only variable that we can alter is the Crr value, or the coefficient of rolling resistance. In order to lower this value and lower the overall watts required to roll the wheel forward, we conducted extensive on-road testing. We proved that a wheel with a wider internal rim width lowers rolling resistance. Our All Sport and Gravel wheels lower rolling resistance by roughly 5%. For the full story, check out this article.

If we look at the equation for the air resistance we see the following:

The only variable that we can alter is the CdA value.  In order to lower this value and lower the overall watts required to roll the wheel forward, we’ve taken the following steps:

1. We developed a computer that mounted to the front of a bike and collected more than 100,000 data point to understand how a cyclist interacts with the air.  Learn more
2. We used this data to develop an optimization algorithm that we use in computational fluid dynamic (CFD) software to solve for the fastest rim shapes we can find.  Learn more here and here
3. We test and verify the results in a wind tunnel.  Learn more here and here

The following charts expand to show you the Total Power for our FLO All Sport and FLO Gravel Wheels using the tire noted. We also show you the estimated time savings for popular race distances. The times savings are based on two wheels. To maximize your wheel performance, make sure your wheels are considering total power in their design.