Tom Dumoulin has admitted he is not a fan of virtual cycling and eSport racing, suggesting calibration and weight registration can impact the results.

The use of indoor trainers and digital platforms to train and race have exploded during the COVID-19 coronavirus pandemic, especially in Italy, France and Spain, where riding outdoors is currently not permitted.

A number of teams have created group rides and races, with many of the riders taking part in races that have been broadcast. The Velon group of teams has created the Digital Swiss 5 series on the Rouvy platform, and Garmin has created the Giro d'Italia Virtual race and rides, while Greg van Avermaet won the virtual edition of the Tour of Flanders.

Dumoulin took part in the virtual Amstel Gold ride last Sunday but has yet to take part in any eSport race as he waits for the COVID-19 pandemic to pass and for racing to eventually return when countries believe it safe to do so. He revealed to Dutch newspaper De Limburger that he is not a fan of indoor racing.

"I understand why it exists and it's better than nothing but it's nowhere near the real thing," Dumoulin said.

The Zwift platform has calculated power curves for each brand and model of home trainer. They also automatically disqualify riders who break through a ceiling level of 5.2 watts/kg for 20 minutes or 6.0 w/kg effort for five minutes – as Thomas de Gendt found out last month – and have a created the Zwift Anti-Doping Agency of volunteers who investigate suspected 'power doping' cases.

However, Dumoulin is not convinced.

"The results are also not reliable; they say nothing. Wout van Aert is really the king of pedaling power and he finished 10th in the virtual Tour of Flanders. The devices come from different brands and are not properly calibrated, which is essential. The weight you enter must be exactly correct, otherwise it will be unfair.

"I rode the virtual Gold Race with an average power of 250 watts. Most riders can't keep up with that but I never overtook anyone. I'm afraid that the problem with the wattages will last forever."

Dumoulin hasn’t raced since last summer due the knee tendon injury he suffered in a crash at the Giro d'Italia. He is now fully recovered and fit but a stomach virus delayed his debut with Jumbo-Visma and then COVID-19 cancelled his spring programme. Dumoulin is expected to lead Jumbo-Visma at the Tour de France alongside Vuelta a España winner Primoz Roglic and compatriot Steven Kruijswijk.

He is based in Belgium, just over the border from his native Netherlands and the Limburg region, so can train outdoors. The Tour de France has been postponed until August 29. Dumoulin will soon up his training but is not optimistic the Grande Boucle will be held, due to the effects of COVID-19.

"At the moment, I'm not trying to ride the bike every day with a specific purpose in mind," he told Limburg television channel L1.

"I try to keep myself fit and set a daily goal. I've worked out a kind of training schedule but it's limited and not necessarily with the thought that the Tour is coming soon because we just don't know if it will happen. If I believe the virologists, I don't give it much chance."