A Zwifter asked me question last week: “Can you supertuck on a TT bike in Zwift?”
“You cannot,” I told him. “I’ve seen it happen occasionally as some sort of weird visual bug, but generally speaking your avatar won’t supertuck if you’re on a TT bike.”
That Zwifter went on to say they had heard rumors that you actually do receive the benefits of the supertuck on the TT bike, it’s just that the avatar animation isn’t there. Like some sort of stealth supertuck or Zwifty quantum entanglement.
Having never tested TT frames for supertucking, I decided it was worth a bit of time to get a firm answer. Especially if thousands of Zwifters will be team time trialing atop TT frames every Thursday moving forward!
Setting Up the Experiment
Testing for TT supertucking on Zwift isn’t as easy as you might think.
This is because (and few Zwifters know this) the physics of descending and supertucking are handled differently in races on Zwift than they are in every other situation. You can read all about this in our May 2019 post “All About Zwift’s Updated Race Descent Dynamics“, but to summarize:
Races
No braking force applied when coasting
Supertuck receives extra aero advantage
All Other Rides
Slight braking force applied when coasting
Supertuck simply removes that slight braking force
To supertuck in Zwift three conditions must be met:
- You must be traveling at least ~36MPH (~58km/hr)
- The gradient’s decline must be at least -3%
- Your power output must be less than 11 watts
For this experiment I used London’s Fox Hill descent. Solo riders would start the descent holding 300W until they hit 60kph, then cut their power completely (if it was a supertucking attempt) or reduce power to 50W.
Since race physics differ from free (or group) ride physics for road bikes, I figured they might for TT bikes as well. So I had to test both race events and free riding.
Speed Test Results
My riders did a total of 8 Fox Hill descents, in various configurations. We did each type of descent at both 0 watts and 50 watts. Zero watts was the supertuck attempt, while 50W was held at other times to keep riders out of the supertuck.
Here are the results (times are from Strava, so there is a bit of rounding occurring):
| Bike Type | Ride Type | Power | Descent Time |
| TT | Free ride | 0W | 2:19 |
| TT | Free ride | 50W | 2:14 |
| TT | Race | 0W | 2:18 |
| TT | Race | 50W | 2:15 |
| Road | Free ride | 0W | 2:27 |
| Road | Free ride | 50W | 2:23 |
| Road | Race | 0W | 2:08 |
| Road | Race | 50W | 2:24 |
- Note: TT bike was a Canyon Speedmax CF SLX, road bike was the Specialized Venge S-Works. Both used DT Swiss disc wheels.
Takeaways
The TT bike’s times between free riding and the race were nearly identical, which indicates that Zwift does not alter descent physics for TT frames based on the type of ride (race vs other rides).
Even though our TT supertuck attempters met all the requirements (zero watts, gradient at least -3%, going over 58kph), our avatar never supertucked visually. Moreover, the TT bike consistently turned in a faster descent time at 50 watts compared to 0 watts. Clearly there is no supertucking going on with TT frames. Not even a stealth supertuck!
This is our major takeaway for TT bike riders, regardless of whether you’re in a race or some other event: on descents, you are better off soft-pedaling at 50W than coasting. Even on steep descents! Simply put, if you’re not pedaling your TT bike, you’re losing time.
We ran the road bike tests just to confirm that Zwift’s physics are still working the way they were two years ago. And they are! The road bike’s times show that Zwift treats road frames very differently from TT frames. Supertucking on the road frame in a race was 19s faster than supertucking in a free ride!
Supertucking gives riders a major speed advantage on road bikes, but only in races. In fact, based on prior tests, we can confidently say that supertucking a steep descent in a race can give you similar speeds as riders holding 300W (4 w/kg) on that same descent.
Conversely, supertucking in a free or group ride is slower than soft pedaling at 50 watts. Keep that in mind if you’re in a non-race event and trying to go fast on a descent! Pedaling even at 50 watts will get you down the hill faster than supertucking if you’re not in a race.
Questions or Comments?
Post below!
I was commenting on this after last night’s Zwift Classics race in Bologna. On the way down the hill after the race I topped out in the mid-90’s while coasting on the Felt 1A 2.0 (rested at the top for a minute then stood up on the pedals at the top of the descent until I hit 60 kph) while I can usually hit at least 105 kph supertucking down that hill in the Tron (if memory serves, the fastest I’ve gone down it without drafting was ~112 kph supertucking in the Tron and have hit ~115 kph supertucking down… Read more »
Brilliant analysis – very interesting that even very low power is better the coasting downhill on TT bike and road bike in freeride.
off topi question.. which kit is that one blue and orange that the avatar is wearing?? Looks pretty nice
That’s the “Prism 2” kit. Unlocked with the Prism pack at level 46.
I tested the same this week (though with fewer samples) and came to the same conclusion – it was clearly faster to pedal than not.
Great info, Thanks! it’s notable however that none of this takes into consideration riding in a pack and the effect of the draft, which of course in a race would be likely unless you dropped…
In the WTRL TTT race last weekend (Makuri Flatland Loop), I stopped pedaling on the downhill after the dragon (?) claw in the field. We weren’t quite going supertuck speeds on the descent (we were just playing with the mechanics and shooting for longest time on course), but I (by far the heaviest in the group) was able to stay in the pack while coasting until the road flattened out. Then I shot out the back like a rocket and had to sprint like a madman to catch back on again as the road descended right before the pens. So,… Read more »
That’s interesting, Paul. Hadn’t though about this particular situation, since Zwift isn’t turning off the braking for TT frames, even in a TTT, it’s just a bad idea to coast at all.
My guess is you dropping off had more to do with losing the draft than anything else. But your whole team, if they were coasting on TT bikes, was losing time on the descent…
The rest of my team wasn’t coasting. I was just trying to see if the draft was at all sticky and would let me hook up with them and coast the way that I can sometimes do in a pack in a race even when we’re not supertucking to just get a 2 second microrest (and was also trying to see what would happen if we got up to supertuck speeds, which we didn’t because we were just playing around). Turns out that I almost could stay attached but need to be extra careful about falling out of the back.… Read more »
Supertucking IRL is dangerous and not allowed in any official Tour anymore. So I don’t understand the relevance of all this.
Maybe you would be more interested in rideoutsider.com, then?
Tell me you have no idea what Zwift is without telling me you have no idea what Zwift is…
I wonder if it’s worth testing this in a team trial event. We know Zwift has changed the dynamics to enable TT draft, and I wonder if they have also tweaked the Zwift dynamics for descending on TTs
Was thinking the very same thing.
Great analysis, definitely answered the question for me (am I the ‘zwifter’ you mention 😂)
Thanks for researching this. This article answered so many questions.
Will learned something new today.
Did not realize that Supertuck was treated differently between rides and races.
Brilliant analysis – very interesting that even very low power is better the coasting downhill on TT bike and road bike in freeride.
Very interesting results. But, my super tuck preference/technique is to tuck with intermittent 300-400 watt accelerations. That world be tough to test!
Interesting results. I tend not to bother supertucking during races, as I find that pedalling at ~100 or so watts allows me to stay in the draft of a downhill pack who are often tucking. I find entering and exiting supertuck to be quite laggy, which can on occasion result in being dropped by a pack, whereas low wattage pedalling to stay with the pack is much more predictable. I’m not sure if this is due to using power meter pedals, but power seems to take a few seconds to drop to zero, and another few seconds to re-engage after… Read more »
@Eric Schlange , is there any information on descent times for other road bikes? For example, how much faster is the Venge S-Works + DT Swiss Disc wheels then the Aethos + Lightweight Meilensteins?
How about in the TT race without draft… Would aero bike still perform in a similar way?