Zwift’s physics, like outdoor physics, are influenced by many factors including rider weight, virtual bike choice, power output, and virtual environment (gradient, air resistance, rolling resistance, etc).
Yesterday’s Zwift update to game version 1.52 included three notes about rolling resistance changes:
- Reduced rolling resistance proportionally across road, gravel, and mountain bike wheelsets when riding on dirt road types.
- Reduced rolling resistance for the ENVE G23 wheelsets to match other gravel wheelsets on gravel and dirt road types.
- Corrected the rolling resistance of the Zwift Mountain bike wheelset on brick road types.
The first change is the biggest news, but I’ll cover all three notes below. Let’s dive in!
Faster Rolling Dirt
Rolling resistance is known as “Crr” in the cycling world (read all about Crr on Zwift), and yesterday’s update significantly lowered the Crr of dirt surfaces throughout Zwift. Here is a table showing the old and new dirt Crr values for each of Zwift’s three main bike types:
| Old Crr | New Crr | % Crr Reduced | Watt Reduction* | |
| Road | .025 | .016 | 36% | 80W |
| MTB | .014 | .01 | 29% | 36W |
| Gravel | .016 | .012 | 25% | 36W |
* “Watt Reduction” represents how much less power riders will need in order to travel at 40kph with the new Crr values. This assumes a 75kg rider on a 7kg bike.
While this change has made the dirt roll faster for all bike types, the change isn’t as “proportional” as Zwift’s note may imply. As you can see, road bike riders are saving 80W with this change, while MTB and gravel riders are saving 36W.
Another way to look at it: if you’re on a road bike going all-out while climbing up the Jungle road (a regular occurrence in races), this change gives you back 80W that would have previously been used to overcome rolling resistance. That’s a lot of watts!
So, how much faster is the dirt? We ran some tests with our bots, using a 75kg rider holding 300W steady.
Our first test was on Makuri Islands’ Kappa Quest route, which features the map’s key dirt section (the Temple KOM climb) plus some tarmac. It’s a great test route to show how changes in rolling resistance affect particular sections and overall lap times on mixed-surface routes.
Old Kappa Quest Times
| Bike | Climb | Descent | Forest | Tarmac | Lap |
| Zwift Concept Z1 Tron (Road) | 7:36 | 2:24 | 1:53 | 5:12 | 17:05 |
| Trek Supercaliber (MTB) | 7:11 | 2:20 | 1:46 | 5:38 | 16:55 |
| Specialized Crux (Gravel) with Zwift Gravel wheels | 7:11 | 2:22 | 1:49 | 5:29 | 16:51 |
| Specialized Crux (Gravel) with ENVE G23 wheels | 7:01 | 2:21 | 1:48 | 5:27 | 16:37 |
New Kappa Quest Times
| Bike | Climb | Descent | Forest | Tarmac | Lap |
| Zwift Concept Z1 Tron (Road) | 6:55 | 2:17 | 1:45 | 5:12 | 16:06 |
| Trek Supercaliber (MTB) | 6:52 | 2:17 | 1:43 | 5:33 | 16:25 |
| Specialized Crux (Gravel) with Zwift Gravel wheels | 6:43 | 2:18 | 1:44 | 5:27 | 16:12 |
| Specialized Crux (Gravel) with ENVE G23 wheels | 6:43 | 2:18 | 1:44 | 5:27 | 16:12 |
A few notes on the results above:
- Previously, the Tron bike was 35 seconds slower up the Temple KOM compared to the Crux gravel bike. Now that gap has shrunk to just 12 seconds, which is right around how long it takes a well-trained rider to swap bikes in Zwift.
- The Tron bike essentially matches the gravel and MTB’s times on the descent, thanks to its superior aerodynamics and newly-reduced Crr.
- Zwift has updated their stock gravel wheels to match the name-brand gravel wheels, so all available gravel wheels perform identically. This is probably a good move. Less confusing!
- You may notice this week’s update also made the MTB faster on tarmac. More on that below.
Jungle Lap Times
Of course, the Mayan Jungle is where Zwifters encounter dirt most often. This is especially true now that Zwift has opened up their southern coast road! How did the dirt Crr change affect Jungle speeds? We did some test laps of the Jungle Circuit:
| Bike | Old | New | Difference |
| Zwift Concept Z1 (Road) | 14:57.8 | 13:35.51 | -1:22.3 |
| Scott Spark RC (MTB) | 13:53.09 | 13:18.05 | -0:35.0 |
| Specialized Crux (Gravel) with ENVE G23 wheels | 13:53.63 | 13:20.22 | -0:33.4 |
Wow! While all three bike types got faster, the road bike got much faster.
To Swap, or Not To Swap?
Prior to this week’s change, riders would often swap to a gravel or MTB when hitting key dirt sections like the Temple KOM or Jungle Circuit in a race. If you were able to swap quickly this was a smart move in many situations, since you could put a lot of time into your non-swapping competitors.
But given the results above, does it make sense anymore to swap from a road bike to a gravel or MTB when hitting the dirt?
Probably not. Certainly, if you’re in a situation where you’ll need to swap from road to gravel/MTB then back again, a swap no longer makes sense because you aren’t saving enough time swapping to make up for the cost of both swaps (approximately 25 seconds).
With that said, swapping may make sense if it’s a one-way swap. For example, if you’re in a Makuri Islands race that finishes atop the Temple KOM, it may make sense to swap to a gravel bike when you hit the dirt, since you can stay on that bike all the way to the finish line. (This would especially make sense if you’re going for a fast segment time and make the swap before the KOM start line).
ENVE G23 Fix
Zwift’s update 1.51 included a config error for the ENVE G23 gravel wheels – they didn’t get updated to roll faster on gravel like all the other gravel wheels. This week that error was fixed, so now the ENVE wheels match the performance of all other gravel wheels.
I already mentioned this above, but it’s worth noting again that Zwift also changed their Zwift-branded gravel wheels to match the performance of the name-brand gravel wheelsets, so all the gravel wheelsets now perform identically.
Faster MTB Wheels
Zwift says this week’s update “Corrected the rolling resistance of the Zwift Mountain bike wheelset on brick road types” but it would be more precise to say Zwift has made their MTB wheelset roll slightly faster on nearly all surfaces.
Along with the dirt change already noted above, this week’s change reduces the MTB wheels’ Crr from .01 to .009 on the following surfaces: Pavement, Sand, Brick, Wood, and Cobbles.
You still won’t be seeing many mountain bikes out there on Zwift roads, but at least they’ll be a bit faster.
Questions or Comments?
What do you think of Zwift making their dirt faster? Will you be doing any swapping in the future? Share below!
So glad they’ve made the dirt faster, a much needed change, as bike swapping was annoying, and dirt just felt too slow compared to road on a road bike, and like all the work you do to present the results of the changes. Something I have been wondering, and not seen around. What difference is a disk wheel with Venge S-works, against the Tron in a sprint. Say a 20-30 second, 1000w effort on a flat sprint (i know draft might make a difference, but sometimes like to lead out from the front). I know it’s going to be minimal… Read more »
The calculation is really simple: take the absolute difference in Crr, multiply by 10 (for gravity), multiply by your mass in kg, then multiply by speed in meters per second. That’s watts saved. Meters per second is kph / 3.6 (so 36 kph = 10 mps). This means 10 is a decent number for speed.
So if the Crr of a road bike changed by 0.009 (from 0.025 to 0.016), then multiply by 10, then 10 again, and you get around 0.9 W/kg saved going 36 kph. That’s huge.
This has been my main hang up with any “fastest” bike claims for racing outside of time trails. It is just hard test to measure acceleration I would think. Prompted first time thinking of a few sims to run though in order to find acceleration differences to the speed tests.
A better solution would be to make it easy to swap bikes than make all bikes nearly the same.
Bike swaps as a tactic, team or solo, is officially dead, which is a real shame. What makes it more of a shame now however is … what on earth are we supposed to do with the gravel bikes and MTBs on Zwift? They literally serve zero purpose now. Which to me is more of a shame than anything. ZHQ should’ve just paved Jungle, and given us Gravel Mountain and some single track routes like climbing up the side of Epic from the new Coastal road. Now they’ve instead gone and ruined a surface type entirely. While gravel bikes are… Read more »
Yep, even as an ATV’er I miss the nerding out before races. Now when you race—> tron. Except when doing AdZ or Ventoux.
but what about the Scotland climb-route? In the past you could benefit by choosing gravel from the start?
I see your point and I unterstand your opinion. To me being able to make a fast bike swap in zwift is not a skill I‘d like to have, and certainly not a skill that should be deciding whether you‘re able to ride for the win or not.
And for MTB and Gravel bikes, yeah no need for those anymore. Thats annoying, as the Garage is generally not super tidy imho…
If it makes you feel any better; it’s not a skill I worked on nor really wanted to work on either LOL! BUT, like Ronald, doing those tests to see which was the right move to do, to make recommendations to teammates… was actually fun, and indeed a bit geeky, but a fun aspect revolving race recons. It’s definitely a bit of a shame; instead of coming up with a real solution that could’ve been not only intuitive, or fun, or interesting, ZHQ just made everything faster… And Ronald is pretty spot on; at this point, why use any other… Read more »
Totally agree on most of your points. Im just very happy, that bike swapping is out of the equation. To a certain extent zwift is a game, so adding other challenges to it is totally fine. For me, zwift is mostly a virtual training platform that makes riding indoor fun. And all I want is to train there through the winter or take Part in some races. I‘m exaggerating here: Imagine UCI worlds (or any other Race) on big Ring or any other route with dirt and a bike swap, and there is one Rider who is just able to… Read more »
Exactly, I enjoyed the big gains you got from mtb and sometimes gravel over road. This move made the game much less interesting for those of us who don’t race very much.
This is great news! I refuse to pause my ride to swap bikes, so I just tried to avoid routes that favored gravel bikes. I’m there to ride, not study the terrain for the fastest bike. I am less concerned that the differences are close enough now.
Thanks for this article, really insightfull. I’m personally really disappointed with this change. I loved how you could swap bikes at the jungle base on the big ring route in Tour of Watopia and just fly by people on the way up. Looking at these numbers it just won’t be beneficial anymore.
At least we’ll still have City and the Sgurr for some alternative bike setups to punish the less informed 😎
They shouldnt mix in the first place.
Mixed roads are terrible and im trying to avoid them.
A gravel world would been better.
This is great news. Previously, I have avoided the Jungle because of the slow speed on dirt, unless I was getting to Alpe du Zwift. But with the expansion to the south coast, travel through the Jungle is necessary. Looking forward to more Zwifting throughout!
Thanks for the testing and explanation, as always. Next request for Zwift HQ? How about a “Garage Sale” function where you can organize favorites and/or delete your Garage of no longer used frames and wheels, and socks and shirts for that matter.
or at least some way of making favorites or something like that.
I think Zwift should focus on complete gravel routes and make a new map for it , imo the textures and routes are to boring like you would do in real life more Farm tracks like in forests:.. Now gravel pieces are just some dust cloud u gather en annoying:
Even if you swap bikes in 10 seconds it doesn’t make sense in a race as you lose the draft.
Eric — random question. Seems like the bots in when go over surfaces on flat route (sandy segments and the wood bridges) absolutely take off. with CRR changes universal do you know why Genie for example at flat 278w would accelerate vis a vis pack riders on non-pavement surface? Or is it just my imagination. Thanks much!
Crr is client side apparently and they slowly roll out new versions, so if the bots got the new crr changes but the pack didn’t yet then that would explain what you see.
This removes a tactical aspect of racing. I guess I would be about pro-choice, and so the removal of a choice isn’t good in my opinion. Can’t see any point of owning mtb or gravel bikes now in game unless they create dedicated 100% dirt surface routes.
This is unfortunate. Basically, this is one more step in making the Tron bike the best bike for almost every situation, which has negated the whole concept of having diverse bike selection and purchasing bikes in the first place. Personally, I think the Tron bike was a mistake from the very beginning and I refuse to use mine even if it costs me a few watts.
The tron bike is THE reason for us game-bikers to feel good about our avatars. If you want to take the fun out of living room cycling, there are other plarforms to cholse from 😂
Interesting to see the descent times are so close. I wonder what these figures would look like including the lead-in from the jungle start pens, to see what the chunk of asphalt plus long descent to the start line do for the overall times in a jungle-only race.
Finally the jungle is rideable again! Thanks Zwift HQ! 🙂
Thanks for doing this – will miss bike changes as an occassional tactic but I won’t miss draggy gravel.
Do we expect similar changes for the TTT – eg the TT to Gravel to TT swap is now pointless? (or at least the same as Tron to Gravel to Tron)
TT bike wheels are the same as road bike wheels, so the numbers above for “road” apply to TT bikes as well.
Bad decision by ZHQ. Dirt still to slow to make it attractive to ride there (#pavethejungle) + they also made the only fun part (swaping bikes) about dirt unattractive.
I would not have minded the slower speeds on the gravel and sand if I could have felt the resistance in my trainer. However, going from road to gravel and seeing no difference other than my overall speed was dropping was kind of annoying. Maybe it was just a function of my particular trainer but the only thing I noticed when riding on the gravel or sand was that my miles per hour just went down.
just to be safe but does the advantage gained with the tron also apply to other road bikes?
Yes, Tron rolls the same as other road bikes.
They need a zwift Craigslist. I have some gravel and mtb bikes barely used For Sale Best Offer.
I stayed away from the jungle as it was always hard work on my roadie. I couldn’t be bothered swapping bikes and never did try an mtb/gravel anyway. I’m glad it’s been made a bit easier for us lazy sods! 😘
Hmm… i don’t like it. Of course, less brain burning about bike choice, but what is the sense of shopping virtual frames and wheels then. All you need is the Tron and Aero is everything. Boring!!
Wonder how the test bot would have done on the OG Jungle CRR ?
My best time is under 13mins from 2019 on a road bike.
With these resistance changes is it even worth Zwift having differential CRR for the various surfaces on the main roads ?
I hated it when zwift made the jungle slower, now I think it’s a shame that it’s not worth switching.
The MTB is currently no longer used. I’m also in favor of changing using a button with preselection.
I’m currently using Zwift Play to change brakes, but that’s no longer worth it 😕
Hey Eric and all!
you think we will ever really get to dork out like in real life and have tire selection and resistance comparisons etc? i doubt we will make it to bearings hahahah
As a triathlete, I enjoyed bike swapping. Like transitions in triathlons, it is another skill that could provide an advantage to those willing to work on the nuances. For pure cyclists, I can see the annoyance, but for this triathlete and gamer, it is a loss to no longer need swaps in some races.
One of my favorite races ever was the Valley to Mountaintop race during Race Makuri a year ago. You had two potential strategies–ride the road bike and use the peloton and draft or ride a gravel bike and blast the first gravel section to get away from all the road bikes in the peloton, try to hold them off on the paved section before the climb, and then go as hard as you could on the gravel climb. I chose the second strategy and did my best 12 minute power ever, gaining over 30″ of time on the peloton in… Read more »
I hate this.
Really hate it to be honest.
Like almost everything in life. People dumb things down to pander to the masses.
Bike swaps, and reconning if they were an advantage was a skill. One that is now removed.
Might as well just make all the surfaces road.
What an awful decision!
Not really about dumbing things down. Swapping bikes is a neat trick, but it’s not really fun in a cycling simular. Not a “who can tap on their keyboard as quick as possible” game.
One presumably unintended result of the crr changes is that they don’t seem to have changed the crr for the Robo pacers. When riding the Wandering Flats route with Maria, the gravel section between Yumezi & Neokyo causes a big split in the group each time as Maria slows dramatically relative to the other riders. To stay with Maria, I had to slow from the 2.2 w/kg average down to about 1.5 w/kg. Most riders didn’t realise this was happening (it took me a while to figure it out) & so were suddenly 35-40 seconds ahead at the end of… Read more »
My bet is this gets resolved on Monday, when they have Robopacer maintenance scheduled.
If all surfaces are levelled up then how many sweat drops have been wasted on the purchasing of gravel and mtb frames and wheels ? Is zwift more interested in speed than giving us an ‘as close as possible real life cycling experience ‘
i think they are abandoning the original thoughts behind the varied surfaces !
I don’t agree with the new Crr changes but I love zwifting ❤️
The problem is that zwift didn’t seem to think through the crr changes when they first implemented varied surfaces. It never really added anything to the game (unless you feel that tapping quickly at the keyboard to perform a bike swap which is impossible in real life is adding something), except slowing you down. So getting rid of it is abandoning their half thought out project that they never really finished to make it a useful or interesting addition to the game.
This really feels like a backward move. I would say can I have a refund on all my gravel bikes, but what’s the point in having the drops anyway. The Tron will be the only bike you need which is a real shame as it has the worst avatar dynamics/no sense of draft. Is ZHQ going to adjust the speed of the DT Swiss ARC 1100 wheels as well? If so please let me know so I can stop chasing the the Km’s to level 42. In fact many incentives vanish with this change.
SEEMS (feels?) like road bikes are still visibly slower even if less so. Given the numbers i wouldn’t think it would be noticeable.Perhaps the difference is much (more than even expected) more for less than 300 watts (a lot of power) where aero gains (exponentially) more importance while crr effect is unchanged/ constant (does this make sense)? I see it in numbers with road bikes around me palpable but less at modest wattages at least.. Even pretty inexperienced Zwifters in a recent ride (who never heard of a bike swaps) asked during a TOW event ‘why am i suddenly going… Read more »
What is the conclusion then if you are riding a race on Jungle Circuit or Serpentine 8? Tron, MTB, or gravel bike?
The MTB is faster according to tested lap times, but what about drafting? Does that favor Tron?
Please see my question. I think it is rather relevant information needed when doing races on dirt surfaces. The route details are not updated so the information cannot be found there.