How precise is this FTP test?
The outcomes of these FTP calculations are as accurate as the input. The physics behind this equation is 100% exact, but to come to an outcome we have to make assumptions. The biggest resistance on the flat is the air resistance. For that it is important to know the frontal surface and how easy the air detaches from the cyclist and the bike. Therefore, it makes a difference if you sit up straight or in a time trial position or if you wear a normal helmet or a time trial helmet. This value is expressed as CdA (drag coefficient times frontal area) and can only be measured precisely in a wind tunnel. With this calculation we estimate this CdA value based on length, weight, type of bike and position. Especially with these estimates there can be quite a difference and the higher the speed the bigger the possible error. Besides that, we make certain assumptions about the rolling resistances and even the air density based on the temperature. Therefore use this calculator as a rough estimation only of your FTP. If you really want to take this to the next level then buy a power meter and do an exercise test in a performance lab.
How to get better?
Getting better is all about timing. There are actually no good or bad workouts. There is only a bad combination or the wrong workout at the wrong time. The path to progress is therefore a training plan with the right training stimulus that takes into account your level, goal and available time.
To help you with that we developed an algorithm in the JOIN Cycling application. It provides you with a highly flexible training plan that helps you make the most out of your rides.
To familiarize yourself with the concept of FTP we recommend reading this article first.