QUESTION: What’s a good FTP on Zwift? I’ve been riding with the app for a few months now on my Wahoo KICKR smart trainer, but I don’t know if my FTP is any good or not. How do you know? – Lee M
ANSWER: We’ve covered this subject in a different way, when someone asked about what a good average wattage is on the road. But let’s keep it strictly in Zwift terms for this answer.
In case you don’t know already, FTP stands for functional threshold power. That is basically your highest average power (your wattage) that you can maintain riding as hard as you can for an hour.
But here’s the problem. The wattage number by itself doesn’t mean very much! Because the lighter you are, the fewer watts you need to generate to go a particular speed. Or put the opposite way, the heavier you are, the more watts you’ll need to pedal to go the same speed as someone who is lighter than you.
That’s why if you race on Zwift, they don’t put you in categories based on your FTP. They use that number, but then divide it by your weight to give you an average watts per kilogram.
As an example, if you weigh 200 pounds and your FTP is 275 watts, then your power to weight ratio, or your watts per kilogram, is just over 3 watts per kilogram. That would put you in the C category of Zwift racing, and it would also give you the power profile of the typical Category 4 bike racer.
But if you weigh 150 pounds and you have that same FTP of 275, then guess what! Now your power to weight ratio / watts per kilogram is just over 4 watts per kilogram. That puts you all the way up at the bottom of the A category for Zwift racing, and give you the power profile of a typical Category 3 bike racer.
Weirdly, Zwift forces you to calculate your watts per kilogram yourself to figure out which category you should be racing. To do that, convert your weight in pounds to kilograms. Take your weight in pounds and divide by 2.2046 to get it into kilograms. Then take that number and divide your FTP by the correct number of kilograms.
Or just go to this page and let them do all the math for you….
Once you see your watts per kilogram number, you can see how “good” your FTP number is for you by looking at which category Zwift wants you to race in.
Here are how racers are split into categories on Zwift.
A = 4.0 w/kg and above
B = 3.2-3.9 w/kg
C = 2.5-3.1 w/kg
D = 2.4 w/kg and below
If you do much Zwift racing, you should also register over at Zwiftpower.com. After each Zwift race, Zwiftpower filters out all the people who are racing in your category who don’t have a heart rate monitor or a power meter, or who ride at a higher watts per kilogram level than is allowed in that category.
So by looking at your results at Zwiftpower.com, you’ll get a better idea of how you actually did against similar riders and you can ignore the sandbaggers or people who didn’t have their trainer set up in a way where you can verify that they were really riding that hard.
“FTP stands for functional threshold power. That is basically your highest average power (your wattage) that you can maintain riding as hard as you can for an hour.”
I know that this is what FTP is stated to be, but I don’t actually think it’s true. Very few people can ride their FTP for an hour, assuming that they’ve calculated their FTP by doing a 20 min test or a ramp test. This doesn’t get to the original question, it’s just an observation.
As to the question of what’s a good FTP, it’s not just a “it depends on your weight.” Some people are going to be A racers and some are going to be D racers. Neither is better or worse than the other.
A good FTP is one that results from your having fun on the bike. Yes, try to improve your FTP. And yes, try to improve your weight (whichever direction that is!). But at some point, your physiology (including your age) will become a limitation. Nothing wrong with that!
Thank you Jeff; that was a useful and thoughtful comment. Been riding Zwift for 9 months post multiple joint replacements to get into better shape and recover strength. And it has worked….I didn’t know what FTP meant until a few months ago and now its a very good indicator for me of performance and goal planning. You’re right….it should be about fun, attaining goals and improving as a rider and athlete. I’m 68 and look forward to many years of Zwifting.
I’ve been under the impression that equivalent power on a trainer/stationary bike is about 80-85% of what it would be out on the road. Is that right?
No. It is dead wrong.
Such a large difference means there is something wrong with your training setup, usually not enough ventilation so you are overheating.
The other key rmain reason is boredom. Riding outdoors you have things to keep you occupied other than your watts number. There is a saying “A watched kettle never boils” which applies to indoor workouts where time seems to pass much slower during interval training. The root cause for Zwfit’s success is that they provide a solution to this possible.
Linked to this the best numbers often appear in competition which tend to be held outdoors. Again Zwift provides an answer to this.
One final reason only applies to outright max efforts measured in a few seconds where you can throw your bike around outdoors more easily and take advantage of terrain to produce a PB
Otherwise its all about the first rule of training. Specificity. The more you do something the better you become at it. If you only rarely train indoors then your power numbers (FTP is an outdated concept see below) will be less than outdoors,. If , like me, you do most of your training indoors, including racing, then your power numbers may well be higher indoors too.
FTP is a much misunderstood and misused measure. It was created by Andy Coggan and he disowned it many years ago. It is out of date now and people really should stop using or caring about it.
Current thinking is far more sophisticated and reflects reality. “FTP” is a measure of “sustainable” power, so something you can keep up for many minutes. It is useful in some disciplines especially time trialling and doing long mountain climb. Much less so in others e.g. sprinters. There are two key variables that make up sustainable power. Time and duration. Duration will be between 40 and 60 minutes or so. An hour is towards the extreme end, that is why the hour record is so hard even for the world’s best.
I covered this plus a lot more in my series on power training a while back.
https://www.roadbikerider.com/power-zones-for-cyclists-explained/
Funny how folks who can’t put up good FTP numbers are the first to bad mouth it. FTP is a measurement and a base line to measure future efforts off of, period.
FTP/kg for zwift cats ignores weight, light riders will struggle on flat races as pure watts is more important.
This approach to cats is very simplistic and it would be more fun to go up and down the cats based on performance – like IRL.
Zwift uses your FTP as a guide for the workouts. That’s all! You need to have some kind of baseline data for the software to give you an adequate workout otherwise it could be too hard or not hard enough! Other than that your FTP is irrelevant. You don’t need to do a test as swift will gather data from your rides (it’s what most do before they hit the training programmes) and apply what it thinks is an acceptable FTP for you for the workout. The most important thing is having fun and getting in shape while having fun. Unless you’re a pro or very serious amateur FTP isn’t worth worrying about and as someone else has already stated those guys use lots of other data now-a-days. Have fun be happy and healthy. See you all in watopia!😁👍