Power analysis: How to average 35mph in a team time trial

Do you want to average 35mph (57kph) on a time trial bike? All you have to do is hold 550w in the aero bars. 

That’s the short answer, which works for most professional riders. But for us mere mortals, such a feat is hard to comprehend. Needless to say, averaging 35mph is exactly what Jumbo-Visma did en route to winning the opening stage of the Vuelta a España. 

We rarely see team time trials (TTTs) in modern cycling. In fact, Stage 1 of this year’s Vuelta was the first time we’d seen a TTT in a grand tour for years. 

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TTTs are an art as much as they are a skill, with each rider taking calculated pulls at eye-watering speeds and slotting back into the draft after a 600w pull. It just so happened that this Vuelta’s TTT took place on the technical streets of Utrecht, on a course that contained 32 corners in 25km. 

Time trialing technology is only getting better, and that’s why we see higher and higher speeds every single year. The TTT is no exception, and it was only a few years ago that a 55kph average speed could net you the win. In this Vuelta’s TTT, averaging 55kph would have put you in 11th place. 

In this column, we’re going to take a closer look at the power that it takes to hold more than 35mph (57kph) on a TT bike. 

Brandon McNulty helped lead UAE Team Emirates to fifth place in the Vuelta TTT with an average speed of 34.4mph (55.4kph), yet they were still 33 seconds slower than Jumbo-Visma. When looking at McNulty’s power file, we can see how much punchier a TTT is compared to an individual time trial (ITT). 

During an ITT, you can expect a nearly-flat power curve, with steady efforts on the straightaways and small spikes out of corners. But during a TTT, we can see McNulty doing huge spikes out of the corners, sitting in the draft at 200-300w, and taking pulls at more than 550w. Here’s a breakdown of McNulty’s TTT strategy. 

McNulty – First third of La Vuelta TTT

Time: 8:19

Average Power: 396w (5.7w/kg)

Pulling at the front: ~570w (7.9w/kg) for 30 seconds at ~57kph

Sitting in the draft: ~300W (4.3w/kg) for 1-2 minutes

Accelerating out of corners: 900-1000w (~14w/kg) for 5 seconds

McNulty’s pacing strategy is nearly identical to all TTT riders at this level. When the speeds are so incredibly high, it takes a massive effort on the front to hold 35+ mph. For the average WorldTour rider with a good aero position, that means holding 550-600w – in the aero bars!

To understand how this works, we need a short physics lesson. 

Speed on a bike (on a flat road) is mainly determined by your power output and aerodynamic drag. The more power you produce, the faster the go. And the more aerodynamic you are (i.e. the less aerodynamic drag you have), the faster you will go. So get aero and produce more watts. That’s how you go faster. 

But the relationship between speed, power, and aerodynamic drag is not linear. In other words, the faster you go, the harder it is to go faster. Let me explain. 

It is relatively easy to go faster when you are already going fairly slow. For example, to increase your speed from 15mph to 18mph, you may need to increase your power output from 150w to 200w.  

Now, to increase your speed from 32mph to 35mph, you need to massively increase your power output. You may be able to hold 32mph at 450w, but you’ll need to produce 600w to go 35mph. At that point, most amateur riders are close to sprinting. 

This is what makes Jumbo-Visma’s battering so impressive. They beat second place Ineos Grenadiers by 13 seconds, and most of the field by more than 30 seconds. That’s a 1-2mph difference at 35+ mph. Keep that in mind as we continue looking at McNulty’s power numbers. 

In the second half of the TTT, McNulty continued piling on the pressure. His pulls got even stronger, and in the final kilometer, he was pulling at more than 37mph (60kph). In fact, McNulty seemed to have plenty of power left in the tank as he was able to take his final pull up to 63kph at 600w. 

McNulty – Second half of La Vuelta TTT

Time: 13:03

Average Power: 404w (5.9w/kg)

Average Speed: 35.9mph (57.7kph)

Final pull: 600w (8.7w/kg) for 30 seconds at 63.1kph

We’re also going to compare McNulty’s speed and power to Sepp Kuss’ ride, where we can see how Jumbo-Visma was maintaining this kind of 60+ kph effort for the entire TTT. Below are two different sections on the course where Jumbo-Visma put significant time into McNulty and UAE Team Emirates. It is scary to think about flying down city streets at 60kph on a TT bike, let alone doing it whilst your front wheel is three inches away from the rider in front of you.

McNulty vs Kuss – Early technical section of the course

McNulty (UAE Team Emirates):

Time: 4:19

Average Power: 388w (5.6w/kg)

Average Speed: 33.4mph (53.8kph)

Speed on straights: 34.8mph ( ~56kph)

Kuss (Jumbo-Visma):

Time: 4:11

Average Speed: 34.2mph (55.1kph)

Speed on straights: 36.7mph ( ~59kph)

McNulty: +8 seconds slower in 4km

McNulty vs Kuss – Middle section of the course with no corners

McNulty (UAE Team Emirates):

Time: 3:03

Average Power: 376w (5.4w/kg)

Average Speed: 36.4mph (58.6kph)

Kuss (Jumbo-Visma):

Time: 2:55

Average Speed: 37.5mph (60.4kph)

McNulty: +8 seconds slower in 3km

Of course, there will be aerodynamic differences between riders and teams based on their individual aero positions and TT equipment. But at the WorldTour level, the differences are only minor. The difference between 57kph and 60kph on the straights is more than just equipment. 

We’ll finish on this note: while the 35mph (57kph) average speed may seem impressive, it is completely hampered by the corners and constant decelerations throughout the TTT. Looking at Kuss’ Strava file, we can see that Jumbo-Visma was doing more than 60kph on every straight section of road and slowing down to about 50kph in the corners. 

If and when professional cycling holds a team time trial not on a technical city circuit, we will see the 60kph (37.3mph) barrier be broken. 

***

Power Analysis data courtesy of Strava

Strava sauce extension 

Riders: 

• Brandon McNulty
• Sepp Kuss