Zwift has truly taken the world by storm. Millions of users have logged more than one billion kilometres on the virtual cycling and running platform, riding and racing their way around Watopia, New York City, London, Richmond, and more. As the platform grows, so has the interest in virtual racing. And in 2020, virtual racing reached a whole new level, going from a niche winter activity to a fully-fledged UCI eSports World Championships event.
As the seriousness of Zwift racing grew, so did the need for data accuracy, including height, weight, and power verification. We have all seen the obvious cheats on Zwift, “winning” a 30-minute Zwift race with an average power of 550w and 7.5w/kg… But harder to spot are the minor cheats and the data manipulators. Those who have messed with their trainer or power meter’s calibration (sometimes unintentionally), lowered their weight by a few kilos or pounds or made their avatar a few centimetres or inches shorter, thinking nobody would notice.
In the world of virtual racing, when the margin between 1st and 4th is often less than one-tenth of a second, these seemingly insignificant factors quickly add up. Thousands of riders have ditched the platform out of pure frustration – the weight dopers and data manipulators can completely ruin the Zwift riding and racing experience. In lieu of all this, the Zwift and virtual racing communities have stepped up to the plate, creating a host of data accuracy checks and verifications to ensure clean sport and fair competition for all.
ZADA (Zwift Accuracy and Data Analysis) and ZwiftPower are two of the organisations leading the way in this department, and teaming up at the highest level of Zwift racing to ensure data accuracy is present at the UCI Zwift World Championships and the Zwift Racing League. Begun as a volunteer-run organisation in 2016, ZADA was reorganised in 2019 and is now made up of anonymous Zwift consultants and employees. The role of ZADA is to verify performances, not individual riders (which is more of ZwiftPower’s job, but more on that in a minute), based on what is considered physiologically realistic. ZADA is pretty quiet about their performance verification methods – like any other anti-doping organisation, you wouldn’t want to reveal your cheater-catching methods to the world – but based on the results, performances, and verification checks done in top-level events of recent years, Zwift racing performances and data are as accurate as ever.
The role of dual recording during racing
Dual recording is one of the cornerstones of Zwift data accuracy and power verification, as many consider it to be the most effective way of determining whether a power meter is reading accurately and consistently. Dual recording is when a rider uploads a secondary power measurement source (e.g. pedal-based power meter, crank-based power meter) in addition to their trainer-based power measurement.
Most top-level Zwift racers ride with their power meter-equipped bike locked into a smart trainer, which also measures power on its own. That way, the rider will have two different power files from the same ride, one file from their trainer-based power meter, and one file from their crank or pedal-based power meter. After their ride or race, the rider can upload their secondary power file directly to ZwiftPower to complete their dual recording analysis for that race – the first and primary power file will automatically be uploaded to ZwiftPower once the rider finishes their race.
ZwiftPower is the ultimate power analysis and race results centre for everything on Zwift. From group rides to the Tour de Zwift, to the Zwift Premier League and Category D crits, Zwift Power has the results and data from it all. There are also segment leaderboards and ZwiftPower rankings for all ages, genders, and abilities. ZwiftPower is free to sign up for and easy to use; and if you plan on racing anytime soon, you should sign up for a ZwiftPower account so that you can be included in official Zwift race results. Just like in real-life, riders can upgrade – from Category D to Category A+ – thanks to solid race results and increases in FTP.
When it comes to dual recording on ZwiftPower, the upload process is simple: riders can log onto ZwiftPower after their race and go to their Profile Page. In the Analysis tab, riders can click Create New Data Set on the right-hand side of the screen, and proceed to upload both power files directly to ZwiftPower – the first data set will be a .fit file from Zwift, while the second set will be a .fit file that riders can upload directly from their head unit device. Some cropping and trimming may be needed if one or both files contains a warm-up or cool-down, but overall, the process is simple, and takes less than five minutes.
Over time, the data analysts at ZADA and ZwiftPower will have a wealth of data to look through for each and every rider on Zwift, including dual recording data which ensures the accuracy and legitimacy of their power meters. A range of 3-5% difference between the two power meters is considered the upper limit for data accuracy, and anything more may be deemed suspect. The more dual recording files a riders has on their ZwiftPower profile, the more confident the analysts at ZADA are that this rider’s data is honest and accurate.
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Weigh-in and height verification videos
Two of the most basic checks that ZADA and ZwiftPower carry out are height and weight verification, which riders typically submit to a private Facebook group called ZwiftTransparency. ZADA spells out an extremely specific, step-by-step protocol for weigh-in and height verification videos: riders start the video by showing their face and the date. Next, they show themselves calibrating their scale, and then weighing a marked weight (e.g. 10kg kettlebell) on the scale to verify the scale's accuracy. Then, the rider steps onto the scale to weigh themselves; and finally, the rider weighs themselves and the marked weight together.
This process is voluntary for most riders – they can record and post their weigh-in videos every day, or once a year – but many top-level eracing events require a weigh-in video within 24 hours of the race start to ensure the highest level of weight accuracy.
One lesser-known performance factor on Zwift is the impact that a rider’s height has on their overall speed. Because of the wind resistance and drafting algorithms in Zwift, a rider’s CdA (coefficient of drag x frontal surface area, quantifying how "aero" a cyclist is) is greatly affected by their in-game height. According to Zwift Insider, a 152cm (5ft.) tall rider will be approximately two minutes faster than a 183cm (6ft.) tall rider at 225w over a fairly flat course, meaning that a rider posing as 10 or 20cm shorter than their actual height could gain a significant in-game advantage without changing their weight or manipulating their power data.
Height verification videos follow a similarly-concrete protocol, with each rider filming a video of themselves standing up against a wall, then marking their height on the wall, and then measuring that height with a tape measure. While these checks may seem a bit overzealous, they have been powerful tools in the Zwift community by creating and promoting data transparency, and taking steps towards ensuring fair competition for all.
ZADA Three Sisters Ride
The Three Sisters Ride is the final data verification check for the top riders on Zwift. Performed and filmed in a single ride, riders complete four different power tests: first, the Hilly Forward KOM (~1:30), then the Epic KOM (~19:00), then the Volcano KOM (~6:00), and finally, a 300-meter sprint (~0:15) to the finish in Downtown Watopia. All in all, the route takes about 90 minutes in total, and riders can spin as easily as they’d like in between each segment, but must complete the route and power tests in a single ride. The ride must be filmed in full – most riders upload their ride streams to YouTube – and posted with dual recording data to demonstrate the accuracy of the rider’s ability and equipment across a wide range of efforts.
The thinking is: if you can do it in a race, you can do it in training. Also included in the test is a pre-ride warm-up and equipment calibration, removing yet another chance for data and power manipulation. All in all, the Three Sisters Test is the final and most thorough test of a rider’s power data and ability, with a number of checks and verifications to further validate credibility.
In the end, ZADA and ZwiftPower have created an incredible network of data and equipment verification in the ever-changing world of Zwift and eSport. Riders of all ages and abilities could be tested and verified, with the elite rankings taking on the most thorough of tests to ensure accuracy and validation in Zwift League Racing and more. There will always be those who try and cheat the system; but with the advent of dual recording, video weigh-ins, height verifications, and live-streamed power tests such as the ZADA Three Sisters Ride, I’d say it’s almost impossible.
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