Zwift version 1.79 begins its phased rollout today. It’s a minor update as far as we can see from the release notes, but there is one interesting change related to FTP detection. Read more below!
“The Grade” FTP Detection Now Gamewide
The most interesting line in Zwift’s release notes is this: Improved FTP calculation that mirrors how FTP is determined when completing The Grade.
Since the early days, Zwift has used a simple algorithm to detect your FTP in the game based on your 20-minute power. That is, Zwift would look at your best 20-minute power average at the end of each activity, and if 95% of that number exceeded your current FTP setting, you would get an FTP increase popup – the most shared screen in all of Zwift!
Then Zwift released The Grade in June 2024, and with it a new way of detecting your FTP based on your average power and time on this particular KOM segment. Here’s more info, taken from my review of The Grade:
…Zwift looks at your average power and time up The Grade, then computes your FTP estimate based on those two figures. Zwift says they can do this with reasonable accuracy because they’ve analyzed the results of over 700,000 FTP tests on the platform and computed a curve which, when combined with an average power number and time value, lets them compute your FTP.
Basically, Zwift has built a lookup curve so any time you set a new power PB in the 8-60 minute range, they can look up that timespan on the curve to get a percentage factor. The game then multiplies your average power from that timespan by the percentage factor, and if it results in a higher FTP than your current setting, you’ll get the FTP increase popup.
Zwift isn’t revealing what this lookup curve looks like, exactly, but it’s not hard to figure it out with some test rides. Here’s our approximation of Zwift’s FTP lookup curve based on today’s tests (the actual curve is surely much smoother – ours is a bit lumpy since FTP increases in our in-game tests were rounded to the nearest whole watt):
Example: if you averaged 250 watts for 15 minutes, Zwift’s system would calculate your FTP as 250*.893=223 watts. If your current FTP setting was less than 223 watts you would get an FTP increase notice when ending your activity.
If this all feels too technical for you, the good news is you don’t need to know how it works. It’s automatic! What’s important for Zwifters is that the new FTP detection algorithm is more flexible than the old one, as it considers efforts from as little as 8 minutes all the way to 60 minutes in length. And this should result in a more accurate automatic FTP setting for more Zwifters, which can only be a good thing.
Note: as before, Zwift’s automated FTP detection will only ever increase your FTP, not decrease it.
To learn more about FTP, read How (And Why) to Take an FTP Test on Zwift >
Release Notes
Zwift provided notes on additional tweaks and bug fixes in this update:
- Fixed an issue where virtual shifting may not return to the default gear when switching between ERG and SIM modes during a workout.
- Improved connection reliability for the Elite Sterzo Smart steering device.
- Fixed an issue that could cause your avatar to not be centered in the Garage preview when selecting head gear, glasses, or customizing facial characteristics.
- The elevation shown in the home screen is now more accurate for the routes Sleepless City in Makuri Islands and Wandering Flats in Watopia.
- Fixed an issue that could cause the Repack Rush progress bar to not reset after restarting the course.
- Fixed an issue that could show an incorrect lap count when late-joining an event after the first lap had already been completed.
- Fixed a crash that could potentially occur when joining an event via Zwift Companion.
- Android
- Fixed an issue that could result in missing ground textures at the top of the Temple KOM in Makuri Islands.
- Fixed a crash that could occur when browsing the Garage.
- iOS, Apple TV
- Fixed an issue that could result in missing ground textures at the top of the Temple KOM in Makuri Islands.
Discuss this update in Zwift’s forum >
Questions or Comments?
If you spotted any other changes or bugs in the update, please comment below!
“Fixed an issue where virtual shifting may not return to the default gear when switching between ERG and SIM modes during a workout.”
I didn’t think you can switch between ERG and SIM mode during a workout. Maybe you meant ERG and Slope mode? Unless Zwift has changed something with the way that workouts operate. Or are you talking about entering and leaving a free-ride block. In this case, the free ride block might be SIM mode, but it might be flat road. You cannot really tell without actually looking for the flat road tag in the ZWO file. The Zwift workout editor likes to slip that tag in for some reason.
I think you’re correct and that we are simply dealing with sloppy terminology in the patch notes. Pretty sure they meant slope mode.
Zloppy terminology.
you can switch off ERG in a [workout] via the popup menu or app, so you can ride at different power in a [workout], rather than when ERG locks you to set watts.
Yes, but when you do this you ride at a constant resistance that doesn’t change with terrain. Hence the differentiation between (constant) slope mode and Sim(ulation) mode which does change resistance with terrain according your set trainer difficulty.
It is my understanding that you can toggle between ERG and Slope mode in a workout. Not between ERG and SIM mode. There is a lot of confusion about this in the community at large. Particularly amongst beginners. The “sloppy terminology” would seem to be based in sloppy understanding.
That curve from 15 to 20 minutes is way too steep, can you ask if ZHQ’s PhD data scientists if they’ve ever ridden a bike?
Let’s use a 300w FTP as an example here. You’d have to hold 315w for 20 minutes to get that 300w FTP. Reasonable. Or you have to hold 335w for 15 minutes. Not even close to the same. That’s the difference between the top of Z4 and low-mid Z5.
“But they analyzed all this in-game data to come up with the curve!!” Yeah they did the same with ZRS and used data that was irreparably biased by circumstances and broke racing worse than it was before.
I think you are downvoted because of the tone of your message, not the content per se. I think you have a valid point and I feel the same way. For shorter durations your FTP seems to be undervalued, when compared to efforts only “slightly” longer this becomes apparent. If you are a more aerobic rider, like you are as well I guess, I would just stick to the longest FTP test you can do 😉
I think racing has been better, wimpy boy
I was very skeptical going into trying the grade test the first time since I needed to hold ~350 W for 12 minutes or so to get my expected results of 310 W FTP. I ended up holding 360 W for 12:00 for a 315 W result. I normally do 5 or 20 minute benchmarks, so I was floored that not only did I hit that target, but I could even do better.
If you actually run the numbers against your power curve, you may be surprised at how accurate that curve actually is. Fits quite nicely for me, at least.
Wandering Fats in Watopia ?
And what about the most important update: emoticons appearing over riders when they drop one?? 😉
That actually rolled out in the previous update: https://zwiftinsider.com/update-1-78-0-136426/
Thanks for deriving the multipliers for converting MMP into FTP. When converted into Joules (or Joule equivalents) the estimated values are very linear with duration, so a CP/W’ model fits them very well; but the values for 8 and 9 minutes seem a bit high, and those for 13-17 minutes seem a bit low. Very interesting.
This is an outstanding comment and spot on. I was kinda just looking at the same in Golden Cheetah. Was noticing that I was over performing this curve around 14 minutes and under performing the curve around 18 minutes. But it is a very small difference.
Thanks for chiming in here, Robert.
When are we getting the bike upgrades?
Early January was the last estimate I heard.
And when will the routes for the Achievements added in the previous version arrive?
PS: I really think Zwift shouldn’t add Achievements for routes that cannot yet be ridden.
Would be nice if Zwift could fix, or at least provide an update, for all the users with Ryzen machines who are encountering consistent crashing of the Zwift app. It’s been happening for weeks and they’ve been completely silent about it on the forums.
I want to ride with the new “FTP detection” today, but I’m stuck on 1.78 and “Check for Update Now” doesn’t do anything. How can I get it to update now ⁉️
There is a script on GitHub: Update Zwift · GitHub
I never tried it though.
https://www.python.org/about/
Now I just need to learn python so I can understand the script to be sure it’s not malicious. Should only take a few minutes …
Drops multiplier resets: I’ve seen this a bunch of times recently whenever venturing to 30m ahead. Couldn’t find where they’d rolled back the increased ranges, so I’m glad to see this was a bug, and that it’s been fixed!
does the algoritm working on groupworkout with rubber band. I know that Zwift don’t do this because of how it measures Watts.
I’m not sure what you’re asking…
I think the question is whether the FTP Detection also works on Rubberbanded Group Rides and he’s asking because he’s not sure because of how the speed is calculated in these rides. I would think it will work, because the Watts are still measured by the Trainer/PM and thus are correctly input.
Sure, it would work fine on banded rides. All that Zwift needs is your power data coupled with time…
My z racing score has increased massively (although still in the lowest group), since I last logged on earlier this week. Is this a result of revised FTP methodology, and is it common
Probably a result of this: https://forums.zwift.com/t/zwift-racing-score-seed-v2-release-december-2024/640588
Hard to keep motivated if the Windows App keeps crashing like this just before the finish. Already cost me over 2000XP but above all broke my will to keep my work-out plan. It worked fine till last update ….
Ik found out that the hybernate/standby might be part of the problem. Since I start Zwift with a fresh rebooted system I haven’t had any crashes this week. Picking up my work-outs next week … 😎
Is there a way to make the mini map arrow larger? It was that way last week and now after this update it’s small again. My eye sight is poor and hard to see that arrow. My tv is only about 3 feet away (32 inch tv) but just can’t figure out which way it’s pointing. I looked at the setting but I can’t see anywhere where it would be updated.
Thanks
With a PC you can click on the map to change views. You can also cycle through views using Play controllers…
I should have put that I’m using AppleTV 4k, I tried moving to the map but couldn’t get to it.