The Ultimate Zwift Showdown

What would happen if the fastest two cyclists in the world raced each other on Zwift? I selected Remco Evenepoel and Filippo Ganna for this matchup, and the great thing is we don’t even need their permission to simulate the race. By the way, this blog post was called “How to calculate your CdA on Zwift”, but it changed as a good showdown like this is way more exciting. We will cover both topics below.

Remco and Ganna have clashed many times on the world time trial stage, often separated by seconds, with the winner often not known until they cross the finish line. Ganna looked unbeatable for years, but Remco has had his number the last couple of years. Their rivalry is even more impressive given their vastly different statures. Ganna towers over most pro cyclists at 6’4” 181lbs, leveraging mind boggling power numbers to overpower his competition. Remco makes the best of his smaller 5’7” 138lbs size with perhaps the slipperiest aerodynamic position in pro cycling. Remco has recently won both the World Championship and Olympic time trials so is wearing the rainbow jersey in time trials year.

While we may not be able to get these two super powers to fit a Zwift race into their 2025 schedules, I set out to find the answer. We know their heights and weights, and we also have enough power numbers to paint a clear picture. The only thing missing is that mysterious Zwift physics that stay well hidden from us, but not well enough. We need to know their CdA (aerodynamic drag coefficient) and also their Crr (coefficient of rolling resistance) in order to find their speed, but Zwift gives us the latter. “Zwift Insider” has some excellent tech write-ups including all the different Crr values used on different terrain, so thanks to them we know Crr is 0.004 for the pavement on Zwift. Now all we are missing is CdA for both riders, so let’s go find those numbers.

Filippo Ganna’s Zwift CdA

Step 1 was change my height and weight to Ganna’s height and weight in my Zwift profile. This part was easy as I increased my height to 6’4” and reduced weight to 181 lbs.

Step 2 was to ride a known Zwift time trial course at a fixed power output. Riding at the same power rules out unquantifiable differences varying power would present to this model. I chose 330 watts as shown in the image below. I’m 200 lbs or 91 kg so I’d be holding 3.6 watts/kg for me and needed a good warmup first as I’d be doing the course again later. I finished with the time Ganna would have had he ridden this Zwift Tick Tock course at 330 watts as shown in the image below. Ganna’s time at 330 watts is 23:59 which is 26.3mph on this course.

Step 3 took required some off the bike work. I plugged all Ganna’s data into Best Bike Split and uploaded the Zwift Tick Tock virtual course. Zwift uses a Crr of 0.004 on paved roads so I had all the values I needed except for Cda. I ran this course at 330 watts and to reach Ganna’s 23:59 time his CdA must be 0.290. Now it was Remco’s turn.

Remco Evenepoel’s Zwift CdA

Remco was next, so I went ahead and changed my profile to 171cm and 63kg and off I went at 330 watts on the same Tick Tock course. The first thing I noticed was how cool it was to suddenly see 5.3 watts/kg show up next to my rider. I was also flying. Living the life of both a Zwift weight doper and height doper at the same time. Shame on all of you, but I can see why you do it. Remco’s final Tick Tock at 330 watts time was 21:57 at 28.8mph. Remco’s randomly generated Zwift image is shown below. By the way if you’re riding a time trial bike you don’t get any draft benefit from the other riders I’m shown passing so the data is solid.

I ran though Best Bike Split again with Remco’s data and came out with a CdA of 0.223. Now I had everything I needed to simulate this highly anticipated virtual time trial event. I sadly changed my height and weight back to normal after this run.

Initial thoughts on their CdA values

Both of these values are well above their real world CdA values. Ganna is reportedly under a 0.19 CdA and Remco under 0.16 CdA in real life. These numbers aren’t published, but we don’t actually need them as the proof is in their actual time trial performances. Taller and/or heavier riders should have higher CdA values because they’re bigger. At first glance it did seem the gap between their Zwift CdA values is larger, but the truth will be in the simulation using their real world time trial power. Ganna is larger, but also produces enormous watts. Would his 70 extra watts be enough to overcome his higher CdA in Zwift?

Ganna and Evenepoel Power Numbers

We’ve seen enough power numbers from both of these riders to know how hard they ride. Remco at one point had his time trial power in a time trial stage on strava (392 watts for 39 minutes if you’re curious) and enough people saw it before he could delete it. Ganna is a bit more transparent and we’ve seen lots of his files. Ganna held 455 watts for a one hour indoor time trial during Covid shutdown, and we often hear he averaged about the same for his hour record. I’m going with 455 watts for Ganna’s 60min power and 385 watts for Evenepoel’s 60min power.

Zwift World Heavyweight Virtual Time Trial Showdown

I had both riders ride the same time trial course 3 times through to simulate a time trial about 1 hour long. The 3 loop course is 31.5 miles long.

Ganna’s finishing time at 455 watts: 1:04:30 at 29.29mph

Remco’s finishing time at 385 watts: 1:02:27 at 30.26mph

There you have it. This race was over immediately after it started with Remco putting over 2 minutes into Ganna. Clearly quite a different result than the real world, but a fun exercise on Zwift all done during one morning indoor ride. You can take this a step further and calculate how many watts Ganna would need to match Remco’s speed: 501 watts. Taller riders, perhaps a moment of vindication that you really are a little slower on Zwift. Smaller and lighter riders that complain about getting dropped on downhills, do you remember that scene in True Romance when Steve Buscemi says while rubbing his fingers together “This is the worlds smallest violin playing just for you”.

As I’ve said before, I think the Zwift engineers are still taking vengeance on larger riders after we had such an advantage in 20 years of Computrainer time trials. I don’t blame them.