Zwift’s last major update included this note:
Various wheels and tires now have different rolling resistance based on the surface they are rolling on. IE, a mountain bike or gravel tire may be the best on the Jungle circuit, while a road/TT bike is fastest on the tarmac. More to come here in a future update.
This weekend’s update to version 1.041097 seems to have rolling resistance working the way Zwift intends, so we’ve started running tests to see how different wheels perform on the course with updated rolling resistance values.
First: About Crr
The change in Zwift’s latest update means the game is now setting a value for the Coefficient of Rolling Resistance (Crr) based on the wheels you are using in game and the type of surface you are currently riding.
Crr is simply a number which quantifies how much friction your tires are creating against the road surface. A fast-rolling tire has a lower Crr, while a slower tire has a higher Crr.
Our educated guess is that, before this update, Crr was a constant on Zwift, not changing based on road surface or wheel type. But now, every time the road surface changes, Zwift checks the Crr for your particular wheel for that particular surface, and uses that value to help determine your in-game speed. Zwift also sends that value to your smart trainer, where it affects the resistance you are feeling in standard Sim mode.
Here’s a snippet from the ANT+ spec showing how rolling resistance is calculated, then used to determine the resistance your smart trainer gives you:
(section 8.10.2)… the standard calculation for rolling resistance.
Rolling Resistance [N] = (Bicycle Mass + Cyclist Mass) x Coefficient of Rolling Resistance x 9.8
Calculating Total Resistance (Simulation) The total resistance applied by the fitness equipment is a sum of the wind resistance, rolling resistance and the gravitational resistance as shown in Equation 8-15:
Total resistance [N] = Gravitational Resistance + Rolling Resistance + Wind Resistance
Speed Comparison: Road Bike
We used Strava’s Effort Comparison tool to compare the speeds of an identical bike setup before and after Zwift’s Crr updates.
The frame used is the Specialized S-Works Venge, with Zipp 858/Super 9 Wheelset. One of the fastest setups in-game. Click here to access the Strava Effort Comparison, or simply watch the quick video below:
As you can see, our test bike definitely slows down in the dirt sections compared to past performances.
Speed Comparison: Road Bike vs Mountain Bike
Here’s a comparison of the same road bike above and Zwift’s new mountain bike, which is supposed to perform better than the road bikes on dirt.
While the mountain bike steadily loses ground to the road bike on most of the course, it keeps up with the road bike (and even gains a little time) on the dirt sections. (More on MTB performance in dirt coming soon!)
What Does It All Mean?
There are a few key takeaways here:
- All dirt sections are slower with road tires, not just the Jungle Circuit (where it’s most noticeable because it’s a long stretch of dirt). The lava dirt around the volcano appears to roll at the same speed as before.
- Soon, dirt performance will be a factor in wheel choice. Currently, all road tires perform the same in dirt, and only the mountain bike (with its MTB tires) performs differently. This will change when Zwift begins releasing more wheelsets, and they may even change the Crr values of some existing wheelsets.
- Expect more dirt attacks. Racers already like to attack in the dirt, where dust clouds mean poor visibility. But the increased resistance on road tires in the dirt means power numbers will bump up even more in these sections.
Your Thoughts
What do you think of Zwift’s Crr changes? Chime in below!
Eric, thanks for the info as always! Have you by chance checked any cobbled sections (Richmond/Innsbruck/London)? I’m wondering if Zwift plans to make those sections perform as dirt or as tarmac….or maybe as their own rolling resistance factor.
I believe users will stop cycling on routes where the ground is not favorable at a good speed. Jungle circuit will have fewer users around
Watopia Flat 3 little part of dirt, if someone not up dated the game they just fly off the front, it really bad if they know it to they will attack at like 8w/kg and open big gap on the group. for now that route is mess up to.
I don’t know how this will work with Tacx Neo users with enabled road feel as it already adds some resistance on those sections trying to simulate the road!
Precisely. I already have to drop one chainring to maintain similar power output to tarmac.
Most folks just want to ride. Let’s not over complicate things… most I guess just want to jump on the trainer and ride / race and not get dropped because they put the wrong tyres on… what’s next avatars with shaved legs.
it could be lonely in the jungle…
Worst update ever!
I agree with the comments above. 100% unattractive update. Making an extra effort to overcome a hill is exciting, having to put on extra power because the road is made of dirt or because I have the wrong wheels is annoying and uninteresting.
We had a ride at the weekend, just after the update, and I was dropped quickly by a rider with a different setup whilst I was riding at a higher w/kg output. I pushed harder and there was nothing i could do to close the gap.
Thanks Eric for the really useful info. What would be really helpful going forward, particularly when gravel specific wheelsets are released, would be clear info on the exact location and extent of gravel sections on different courses – so an informed decision can be made on bike setup as it is now by looking at route profile and deciding on whether to go lightweight for example. Maybe you can look to add more info on this to your route maps & details pages? Or if a clear guide to this exists, please point me to it, thanks!
Seems bizarre that the MTB would keep up with, or even pass, the road bike on the dirt section. The jungle loop doesn’t appear to be that gnarly. We have a local dirt towpath that I can maintain 20+ mph on my road bike.
This would seem to be the place for a gravel bike/wheel setup…
Am I missing something? I cannot see MTB/gravel bikes/tyres in the swift drop shop.
Yes! Read this: https://zwiftinsider.com/unlock-zwift-mountain-bike/
Zwift is good for users when it was just hop on, pedal, join events and meet friends acrossnthe world. With the recent bugs resurfacing and further complicated by more variables like rolling resistance, is this what we really needed?
The wheel has always been round Zwift, please don’t go reinvent something in the name of creativity or realism… we could just call off the subscription just ride outside, bad weather or not… or on another platform. Honestly.
You have to win the MTB on the new Repack Ridge course with steering. Must get 9 out of 10 stars and finish in less than 12 minutes or something like that.
I kind of like where they are going with this. Being able to rocket through the Jungle Circuit on a TT bike without any consequence always felt more like a bug than a feature to me… that would be terrifying IRL. Weight and aerodynamics have been a factor since day one, so it’s not like equipment selection for a given route has ever been meaningless.
What would be nice to see along with this is a better description/rating of the equipment in the drop shop. The current “star” system is not very informative when comparing bikes and wheels. Something more granular and future proof is needed.
I believe Zwift is doing too much “gaming” with features like this. Most of us road riders just want road to train and race on. Maybe separate the off-road sections to the mountain bikers. Road racing should have no dirt sections or gravel at all. The rolling resistance should just remain the same. Please change it back.
I really dont get it. Zwift seems to be developing only when it can make money, with racing. From an economical point of view defensible, but a lot of riders dont race. They expect bugfixes (log off and on for new ride, how long is that on the fixlist?), new roads, bikes, challenges etc. I think they dont like to ride 8kmph slower in the little dirt sections between the boardwalks… at least i dont
I completely agree with Darrick – I’m not at all interested in steering or rolling resistance stuff. You could maybe make an argument for some races using this (not all) but for group rides it’s completely pointless and just spoils things. Please just put it back again – it was great how it was!
Very nice fun and real world like. More tactics, choose gravel tyres and attack during jungle loop gravel section if you have power, when racing on big loop or road to ruins circuit!
Interesting…but garage should be easier to use if going this route. I want to pull a preconfigured bike from the opening screen maybe, have a climbing setup, a gravel setup, an aero setup, not dig into the garage and put together a frame and wheelset while I’m struggling to warm up and late to the starting pen.
+1
Replying on this site never works as expected. +1 elwas meant to David’s comment: “Most folks just want to ride. Let’s not over complicate things… most I guess just want to jump on the trainer and ride / race and not get dropped because they put the wrong tyres on… what’s next avatars with shaved legs.”
To reply to someone’s comment, hit “reply” to the bottom-right of their comment, then type your reply in the text window that pops up. That’s what I’m doing here!
I’m not a fan of having to change my wheels each time I want to ride a course. In real life, I would have two or three bikes which I can pick for different rides. Road, TT, MTB. It would be good to easily choose n the same screen which bike I use when selecting the course I want to ride, rather than adding a new step. I also unlikely to enter any race now that heads to Alpes as you would have to stop and change bikes before hitting slopes. Also don’t like the dirt sections on watopia forward now having the main impact on race outcomes, where the sport in that. If you are going to have the resistance, then separate the courses and make bike choice far easier.
I do really like the idea down the road of having steering and rolling resistance linked to surface,,,how fun to have a Strade Bianche or roubaix kind of race, all drafting and no steering on tarmac, then hit gravel/pave sections and steering and resistance kick in, trying to follow smoothest line, pass other riders, etc. Combine that with easier, quicker bike selection at race start and I’m totally in…
This update just SUCKS BIG TIME. It has basically ruined group rides that now get blown apart on flat dirt roads. Personally I’ve found I have to put more power to ride downhill on the dirt than I do riding up a 6% climb on normal roads using the Tron bike
I know Zwift wants to innovate but this update is just plain terrible in all respects and it ruins the whole experience. Zwift please ditch this awful feature asap
I don’t mind the update, but I don’t want to fuss with my Apple TV controller and waste time choosing equipment before each ride/race. It would be really helpful if Zwift pre-selected an optimal wheel setup for every race/ride that I did based on the route. Maybe that could be a toggle on/off feature in settings.
Well, we may as well make lemonade. Is there a listing of wheels/tires for road bikes that work best on dirt? Conversely, is there a list of wheel/tire that are worst. I lead low-wattage rides with a fair percentage of beginners, so I may be MOST interested in ones that don’t require you to reach Level 36.
Can this be switched off? Or are there a set of tyres that don’t use this new feature?
No to both questions…
This update has, to be honest, soured the Zwift experience for me significantly. All I want to do is pick a route, hop on the trainer, and ride. If I’m racing? I think it’s a different story. But between the mid-ride crashes, login compromises, and now this, it’s tremendously frustrating.
Agree totally. The ultra competitive types (you know who you are) will be the ones tweaking constantly. The majority of the rest, we’ll avoid major dirt sections. Some might not ride tarmac if you want dirt , but why would you? ‘ )
Have to be honest … really disliked this. And not just that the jungle section is now so frustrating where it used to be one of my favourites.
I have neither the time nor inclination to try and get my Zwift setup capable of steering the front wheel so I can attempt to obtain the mountain bike to remove some of that frustration, so the fact that this has been released without any other options for maintaining some level of performance on the dirt/gravel tracks is just ridiculous. Even releasing a couple of sets of gravel wheels that I could buy with drops and add to my garage would be something.
This … no. Big fail for me.
I really dont want to have to worry about what tires i have or what set up is better for which road. Maybe just just make it an option so if someone wants it they can choose to have it. Me..I prefer NO
I totally don’t care for it at all!! I don’t want to have to figure out what tires to have etc.. please NO. Maybe u could just make it an option so if a person wants it they can chose it
Agreed. The tron bike seems to be super hard on dirt. I put out way more watts that others on non-tron bikes.
The Tron is getting to be less and less of an advantage, but at least it still looks cool.
So much for improving on Strava segments in the jungle . . .
This certainly also affects the wooden boards at the Watopia Pier too. Race starts just became even more ridiculous! I’m not a fan of this at all, but rolling back now will cause the same headache we already have. We now need everyone on the same version to play the ‘same’ game, otherwise its a total game wrecker for races and social group rides. Sadly this was really badly implemented and planned by Zwift.
I think I like this idea. I rode the Jungle circuit this weekend (not knowing about this update/feature) and just noticed that I was going a lot slower than I expected. Makes sense now 😉 But: I (think I) did not feel a higher resistance on the trainer (tacx Flux Smart) when going from tarmac to gravel, Zwift just said I was going slower. Is this a limitation of my smart trainer, is this as it’s intended or is it a bug? It felt like one 😉 I’d expect a rather sudden increase of resistance when hitting gravel. That would give me the feedback to understand what’s going on. Instead, just the displayed speed changed (that I rarely look at). I hope that gets better in future updates. Maybe it should be a setting that can be turned on and off. Events/group rides could trigger this setting so that everyone rides with the same setting – but is aware of it.
Completely agree that this is massive over-complication, and it cracks me up that they timed this release to coincide with new starting pens for the jungle circuit. I rode the jungle last week and was really struggling to figure out why it was so much slower, but oddly NOT on the dirt: the lowest speeds for the same power output came on the wooden bridges in the tunnel. Like almost 5mph slower on the same bike for the same power. That’s insane. Is the jungle circuit going to become the ‘go-to’ course for dirt crits, gravel races, and mtb? Can I get a “This is stupid” button in the game to roll back changes?
Agree
I like to improve and compare my times on various routes and segments. This is meaningless now on every part that includes dirt or board as the circumstances has changed. It is to difficult to beat old times even thoug new efforts are better. Very dissapointing! I just want to cycle and compare my efforts over time. Zwift, please revert this update.
I am so disappointed. I like to improve and compare my older rides on courses and segments, many of them partly on dirt or board. This is now irrelevant as Zwift slowed down my bike slot. Bye, bye jungle and possibly Watopia that I have enjoyed so much.
I feel cheated by Zwift on this one – why don’t they just introduce a MTB World and leave the other Worlds alone. I don’t use a mobile phone on my bike (just like in a Car – it’s dangerous!), and why would I want to steer by jiggling the handlebars anyway since I’m in my garage doing training. Now you have monkey’d with the Jungle section – I want the whole Alpe du Zwift moving – please (yes the whole mountain)! I just feel Zwift is slowly but surely moving AWAY from a serious training and fitness platform. It seems like changes are being made without reference or discussion with the customer base.
BAD IDEA ZWIFT !!!
Thanks Eric, excellent info as always. Agree with most of the above, too much like a game, added “fiddliness” of having to change tires, bikes, etc. will have me looking at other routes, or even other platforms, I also love Rouvy. I can think of many other updates that would have been a far better benefit from my monthly contribution.
Guess I see it differently than most. Part of the fun of IRL (in real life) cycling is the gear choice for the routes you ride. This update simply brings zwifting closer to emulating real life experiences. I do think having this as an event option is a good idea… let the even organizer decide if they want the rolling resistance or not..
Agreed! Worst update ever. I used to like having the jungle as part of my workouts and rides. I especially like when races or fondos used the jungle.
Now I won’t go there. It’s like the jungle route update doesn’t exists for me. And so much for trying to beat my jungle route out n back PR. Hopefully Zwift HQ will come back to common sense. Probably won’t ride the Aple de Zwift either due to this BS.
Are we able to roll back this update? It’s all very well having this update, however, as I use the circuits as a performance benchmark, it’s of no use whatsoever. I find it a hindrance – so much so, I think I’ll go back to trainer road!
Very true – an option not to have this would be good. For someone following a training regime or trying to beat their PBs, it’s of no use – taking the enjoyment out of watopia – never thought of Zwift as a ‘bike simulator’. Cancelled my subscription – if I wanted to MTB or Gravel, I’d just go out!