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!
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