Zwift suspends two riders for data manipulation

The two are the latest Zwift racers to run afoul of the game's rules regarding data manipulation

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Zwift announced Tuesday the six-month ban of Antonina Reznikov and Selma Trommer for altering their performance data.

The ban from official Zwift cycling events is retroactive to January 11 and January 18, respectively.

Both athletes were found to have exhibited misconduct through “fabrication or modification of data” and also “bringing the sport into disrepute” according to the Zwift performance verification board.


Reznikov is a long-course triathlete who finished in third at the 2020 Israeli road national championships won by Omer Shapira (Canyon-SRAM).

It was found that for the Zwift Racing League (Season 2) Women’s Race #1 on January 11, Reznikov submitted race power data that did not match other data submitted.

“Zwift’s automated systems identified that the dual-recorded data from the rider’s power meter may have been edited and warranted more detailed investigation,” the Zwift Performance Verification Board wrote. “Detailed analysis by Zwift of the rider’s data identified that the power values submitted were 32 percent higher than the originally recorded values.

Reznikov initially denied any tampering, but when presented with the discrepancy found during the ZADA investigation she admitted to altering data.

“Zwift discussed the issue with the rider, and although they initially denied editing the file, they eventually acknowledged that they had indeed changed their power data before submitting it to Zwift,” indicated the Zwift Performance Verification Board decision. “The Performance Verification Board considers that it is beyond reasonable doubt that the rider intentionally manipulated their data.”

The full Zwift Performance Verification Board Decision for Antonina Reznikov is available online from Zwift.

Trommer, 10th at the 2020 German national road race championships, triggered Zwift’s performance evaluation algorithms for the Zwift Racing League (Season 2) Women’s Race #2, on January 18, when power values varied from submitted data and appeared to have been altered.

Trommer’s race data varied by about 9 percent compared with her verification data. She claimed technical issues caused problems when files were collected by Garmin Connect and required the use of Golden Cheetah (a third-party power data analysis tool) to move data.

In the Zwift Performance Verification Board Decision, it is noted that “Zwift considered in detail the possibility that the files could have been edited by accident through the rider’s use of these applications. The fact however that all the power records in the rider’s data file had all been increased by a fixed percentage, precluded this possibility.”

According to the Zwift Performance Verification Board Decision, Trommer was offered opportunities to explain the data discrepancies, however, she could not provide an explanation for the data discrepancy, nor took responsibility for data anomalies.

“In order to give the rider the opportunity to put their side of the case forward, Zwift shared digital forensic evidence showing that the data submitted had been edited, and they were asked for their response. The rider gave multiple replies over the next 24 hours repeatedly denying that they had edited the file. Notably, at no point did the rider admit any fault, show any remorse or offer any plausible explanation as to how their file came to be edited,” reads the Decision.

“After extended correspondence, the rider eventually acknowledged both that the data had been edited, and that the principle of strict liability applied. The rider still did not however admit any personal fault, or offer any explanation as to how their file came to be edited.”

The full Zwift Performance Verification Board Decision for Selma Trommer is available online from Zwift.

Reznikov and Trommer are the latest athletes to run afoul of Zwift’s rules. Shanni Berger and Lizi Duncombe were caught by automated systems last fall when they modified files submitted for racing events. Duncombe defended herself, maintaining innocence, while Berger made no statement. Berger’s team Saris-The Pros Closet immediately dismissed her. They will be eligible to return to competition at the conclusion of their six-month bans from racing — Berger on February 18 and Duncombe on March 20.

At the premier level, Zwift requires power files from an external power source (e.g., crank- or pedal-based power meter) to be submitted in addition to the file generated by racers’ smart trainers. Users’ files are compared against each other, as well as to game files maintained on the Zwift servers. Any discrepancies in values in the data files may trigger an automated evaluation and comparison of the files. If further investigation finds intentional data manipulation or tampering, riders may receive a short-term ban from racing. If a rider is discovered to have manipulated data on more than one occasion, or have committed more egregious rules violations, a rider may be excluded from Zwift racing for longer time periods, or even be served a lifetime ban.