FTP, otherwise known as Functional Threshold Power, is a common term thrown about, most often by more serious road cyclist or XC mountain bikes. However, the average trail rider, or recreational road rider may not have any idea what their friends are talking about after a long block of training.
First off, some definitions:
FTP: Roughly the amount of power a person can hold for around 1hr measured in watts (w).
W/kg: A person’s FTP divided by their weight in kilograms. This is the metric usually used to compare riders, as a bigger rider probably has more watts, but has the same w/kg as a small rider because of the difference in weight.
% of FTP: Most commonly used when discussing a certain part of a workout, % of FTP is simply the power you held divided by your FTP to get a certain % of FTP
Ramp Test: A test generally taken on a stationary trainer that starts out easy and bumps up the power by a certain amount after every fixed interval of time (usually 1min), the rider goes until exhaustion, and an algorithm calculates your FTP from there.
So, with all that taken care of, how is FTP useful? Well for one, the number is a good measurement of your ability to use oxygen and fuel your muscles. One hour is also not an extremely intense effort, nor is it a long and slow effort. FTP sits right in the middle, serving as a good baseline for how strong you are over a period of time. As your FTP gets higher, your power for a long 5hr endurance ride rises with it, consistent riding makes your FTP go higher, boosting your overall power. If you intend to do any workouts with a power meter or a smart trainer where you are using power to guide your effort, then you MUST know your FTP before you begin. This usually consists of taking the afore-mentioned ramp test, and having a computer spit out your FTP. An example workout to build endurance and increase your FTP would be to ride at 70% of your current FTP for 1.5hrs and to do that three times a week. So if your FTP is 200w, then 70% of that would be 140w, so you would ride at 140w for 1.5hrs.
Generally your FTP is what people use to compare how fast they are to each other. However, as mentioned earlier, a bigger rider will usually have a higher FTP than a smaller rider. To compare apples to apples then, w/kg is used to compare as it takes both weight and FTP into account. For example, let’s say Rider 1 weighs 80kg and has an FTP of 250w. Divide 250 by 80 and you get 3.13. This is Rider 1’s FTP in w/kg: 3.1w/kg. Now let’s say Rider 2 weighs 65kg and has an FTP of 203w. This also puts him at 3.1w/kg. See how both riders are at the same w/kg even if they are completely different otherwise? This helps create a level baseline for comparison.
So what is a good FTP? As a general rule, pro cyclists usually sit at around 6w/kg or maybe around the 400w FTP range. (Keep in mind, these people get payed to train, and usually don’t have other responsibilities) A very fast amateur might be at 5w/kg, while a mid level rider would be closer to 3.5w/kg. For a beginner with little to no endurance training whatsoever, under 2w/kg is often common. To a certain extent, genetics will play a part in this, but everyone with enough time can certainly be quite a bit faster than they are now. There are many stories about the people who went from under 2w/kg and significantly overweight, and transformed into a fit healthy individual at over 4w/kg.
Generally FTP is used to compare riders, establish a baseline for workouts, and to brag about on online forums.