The supertuck has long been used by Zwifters as a way to grab a quick recovery on descents during hard efforts. Zwift’s update in early May included a modification to the supertuck algorithm which should make it more useful in races. Here are the details, with some insights from Zwift’s Jordan Rapp.
Downhill Braking
There are many physics tweaks Zwift has built into the game to improve our experience which Zwifters don’t even notice consciously. One of those things is Zwift applying a slight braking force when going downhill. Why? Well, one reason is: we don’t have brakes! In a situation where you are riding with a group and you go off the front, then want to rejoin the group, the slight braking force allows you to soft-pedal and be caught by the group behind you who is pedaling harder or supertucking.
Prior to May’s update, supertucking seemed to improve your aerodynamics because it removed that slight braking force. As Jordan puts it:
In the supertuck, your aerodynamics weren’t actually improved, they just weren’t penalized so it seemed faster as a result.
Decent Descent Dynamics, Documented
Today, the supertuck continues to function as described above for all rides except races. In races, the following changes have been made:
- The braking force when descending has been entirely removed. So racers are now faster descending even when pedaling.
- With the removal of that braking, Zwift needed to actually “bump up” the supertuck to make it properly more aero. Zwift isn’t sharing the exact numbers, but Jordan says the supertuck’s aero advantage is similar to the aero powerup (which reduces your CdA by 25%).
Jordan notes:
And, yes, it can be stacked, so supertuck+aero power up will be REALLY slippery.
The changes only apply to races and not group rides or free-riding because, Jordan says,
… Zwift remains, fundamentally, a way to get a great workout indoors and in a short period of time. We didn’t want to disincentivize people to pedal on the trainer. Just sitting on a trainer not pedaling feels pretty weird (and isn’t super comfortable), so we didn’t want to make people feel like doing that was the fastest way to get down a hill.
Of course, in races it is totally normal to sit in and rest on descents, so it makes sense to treat races differently. These changes should help make race descents a bit more variable and tactical, which sounds like a good thing to us. Ride on!
Always nice to see improvements to the racing on Zwift as that’s mostly what I do on it.
what effect on this does the trainer difficulty have?
None, really. I suppose if your trainer difficulty is set very low you’ll be able to pedal harder on descents without spinning out, and this change would let you go even faster when doing so. But basically, I would say trainer difficulty doesn’t really interact with the changes above.
There is no super tuck on time trial bikes, right Eric? Just road bikes.
Correct, Zee!
Hm, interesting. I admit descending without pedaling is pretty dull on a free ride in Zwift. BUT I really love jumping off the bike after peaking at Alp de Zwift, have a toilet break, stretch, get a drink and come back to the bike and my avatar is still going fast. Great way for a break in a longer ride without “stopping” ;).
Do we know which is faster on a just a descent of the Alpe; supertuck on an ‘average’ bike (like Zwift Carbon or Allez Sprint) or using a TT bike, like Zwift TT or the P5?
Not sure which is faster between a supertuck “normal” bike or a TT bike coasting. It’s a weird question, of course, because you’re never really in a situation where you need to decide between the two, right? Most races outlaw TT bikes, so you’ll be supertucking anyway.
Yay, hopefully this will help with me getting dropped on the descents all the time in races.