How realistic are Zwift’s climbs? We’ve compared virtual mountains to the real thing

With the seasons changing, a lot of us will be swapping the road for indoor training. For a lot of indoor cyclists, Zwift is one of the most popular indoor training platforms that people use with a multitude or virtual worlds and routes. A big part of the appeal of Zwift is the inclusion of virtual famous climbs that we can test ourselves on for personal bests, against our friends, or see how we compare to the fastest riders in the world. But just how realistic are these virtual climbs compared to the real thing? To discover what differences there are between them, we’ve looked in detail at Box Hill, Alpe d’Huez (du Zwift), and Mt Ventoux (Ventop) to see how they compare.

Box Hill

One of the most ridden Strava segments in the entire world (ridden 1,404,940 times by 128,680 people), Box Hill hit international fame with its inclusion in the 2012 London Olympic Games Road race route. Tackled nine times in the men’s race and twice in the women’s, while also being a staple of the Ride London sportive while it did the southern loop. The climb features two switchbacks and an average gradient of 5.2% on the official Strava segment over 2.29km with 119m elevation gain.

The Verified Zwift segment is ever so slightly different, with the KOM starting around 300m earlier and finishing 500m later giving a total length of 3.01km with 136m elevation gain and 4.4% average gradient. Unfortunately, it’s almost impossible to compare the KOMs between the two, since the Zwift segment appears to have some anomalous results at the top of the leaderboard. 

But let’s take some known results – Back in 2020, while I was racing for a UCI team, my best time virtually was 5:31 with a vertical ascent in meters (VAM) of 1477 with a power of 464w and weight of 72kg, giving an average speed of 32.8kph. Funnily enough I did more power on another attempt but the fastest was mid-Erace showing the benefit of virtual drafting.

The current real KOM is held by Dom Jackson who did 4:05, 518w, 1750 VAM, and held 33.7kph average speed. This was done with a team leading out over specific parts of the course and planning every element of the attempt. Even faster genuine times up the Zwift version are not as fast as this, even when accounting for the shorter distance of the real KOM.