UPDATE: Zwift greatly improved their banding algorithm after this post was published. To see current “keep together” test results, read the updated post.
Have you ever done a “Keep Together” ride in Zwift? In this mode, all riders in the event are kept in the same group, regardless of the power you’re putting out.
“Rubberbanding” makes it easy to keep a group of cyclists together, and that’s a good thing, because any ride leader will tell you that keeping cyclists together without some artificial help can feel like herding cats!
A Short History of Rubberbanding
Rubberbanding or “Keep Everyone Together” mode has a colorful history on Zwift. It was first introduced when group workouts arrived in 2017, then quickly throttled to lower speeds after lower-power riders complained they were setting segment PRs in workouts.
For a couple of years, rubberbanding was only available in group workouts, and group workout packs moved notoriously slow. But then “Keep Everyone Together” was added as an option for Meetups in October 2019… and all hell broke loose.
The problem was that rubberbanded Meetups had a major speed bug. Groups would speed up over 45kph for no good reason, topping Strava leaderboards (see Box Hill as one example). And this went on for much too long (three years or more).
While rubberbanded Meetups were zipping around at silly speeds, Zwift rolled out Clubs, and eventually launched Keep Together Mode for Clubs in November 2023, along with updated “Keep Everyone Together” logic that replaced the speed-bugged logic used for Meetups.
Testing the Rubberbands
So how does Zwift’s “Keep Everyone Together” logic work? I’m not entirely sure, and Zwift isn’t revealing the secret sauce. So I decided to run some tests using rubberbanded Club events to find out what speeds rubberbanded riders reach at different power levels. For science!
The question I wanted to answer was: do rubberbanded speeds make sense? Or are they too slow, too fast, or some strange mix of both?
The riders in these tests were 75kg in weight, 183cm tall, and rode Zwift Carbon bikes with 32mm carbon wheels. I timed the riders on the Fuego Flats Reverse segment since it’s flat and long enough to get a stable speed reading.
Test 1: A Pair of Bots
This first round of tests used just two riders in a Club event with “Keep Everyone Together” mode enabled. Here are each rider’s power outputs, segment times, and average speeds.
| Rider 1 | Rider 2 | Time | Speed (kph) |
| 300W | 300W | 13:00 | 32.58 |
| 300W | 225W | 13:21 | 31.73 |
| 300W | 150W | 13:21 | 31.73 |
| 300W | 75W | 13:21 | 31.73 |
| 300W | 10W | 13:27 | 31.49 |
| 225W | 225W | 14:45 | 28.72 |
| 225W | 150W | 14:49 | 28.59 |
| 225W | 75W | 14:49 | 28.59 |
| 150W | 150W | 16:13 | 26.12 |
| 150W | 75W | 17:12 | 24.63 |
Observations
The first thing that stands out here is how slow the times are, particularly when the riders have matched power numbers. I know from other tests that solo free riders complete the segment at these approximate speeds:
- 300W: 40.23 kph
- 225W: 35.95 kph
- 150W: 30.81 kph
Why are rubberbanded riders moving so slowly, when they’re both holding the same power? Clearly, something in Zwift’s Keep Together logic is artificially slowing the riders.
The other odd thing is how the pair times don’t change as the weaker rider’s power decreases. That is, when Rider 1 is holding 300W and Rider 2 is holding 225W, they’re traveling at the same speed as when Rider 1 holds 300W and Rider 2 holds 75W. That’s strange. Shouldn’t groups travel significantly faster if the group’s average power increases significantly?
Test 2: Solo Rider
Next, I wanted to test if a solo rider in a rubberbanded Club event still traveled as slowly as the paired riders above. So I created an event with “Keep Together” enabled, but only had one rider join. Here are the results:
| Rider 1 | Time | Speed (kph) |
| 1000W | 9:01 | 47.01 |
| 300W | 13:51 | 30.58 |
| 225W | 15:22 | 27.57 |
| 150W | 17:53 | 23.69 |
Observations
First, notice that when there was just one rider in the rubberbanded event, their speeds were still much slower than they would be when free riding. That’s goofy.
Also, notice how the 300W, 225W, and 150W solo tests all came in a bit slower than the paired rider tests, even when the slower paired rider was doing very low power. For example, a solo rider at 300W traveled at 30.58kph, while two riders holding 300W and 75W traveled at 31.73kph.
Shouldn’t the pair with a very slow second rider move slower, as the rider holding just 75W slows down the overall group?
The 1000W test is also interesting, since it’s sort of a “max speed” test that shows just how slow banded rides may be. In rubberbanded mode the rider only reached around 47kph, while in free ride mode the same rider holding 1000W reaches around 62kph. Or another way of looking at it: ~460W in free ride mode will get you the same speed as ~1000W in “Keep Everyone Together” mode. Sorry, sprinters.
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Other Rubberbanding Discoveries
In the course of these tests, I also asked and answered a few Keep Together questions I’ve seen:
- When does the elastic snap? When a rider drops below 10W, they’ll drop from the group.
- Can you rejoin the banded group? Yup. In my tests with two riders, if a rider dropped back about 30 meters and then increased their power to 10W, they would rejoin the group. If they dropped back 40 meters before increasing power, they would not rejoin. (This “rejoin window” may differ based on group size, like it does for RoboPacers.)
- If a rider is lapped, can they rejoin the group even though they’re “behind?” Yes. Same behavior as noted above.
I also noticed a few things that surprised me:
- Coned riders disappear: one of my bots got the “cone of shame” for holding high power for too long. When that happened, the bot disappeared from the group ride. Well, sort of. It was more like a shadow ban: the shamed bot could still see the other rider, but the other rider didn’t see the shamed bot anymore. This is actually pretty cool, although perhaps Zwift should notify the coned rider that they’ve been hidden. I’m guessing this is how Zwift now treats coned riders in all events.
- Pairing screen doesn’t stop you: if you’re pedaling along in a Keep Together ride and enter the pairing screen, your avatar doesn’t slow. This is counter to pairing screen behavior everywhere else in game, where entering the screen is like hitting the brakes!
- Except when it does: interestingly, if both riders in the Keep Together ride enter the pairing screen, then they both stop.
Concluding Thoughts
Keep Together mode has always been popular in Zwift because riders want to be together, and the magic of Zwift allows riders even with very different abilities to go hard but stay together. That’s a big deal! So even when it was broken and zipping people around at silly speeds, people kept coming back because cycling is a social sport, cyclists are social people, and Zwift is a social platform.
Yes, rubberbanding is popular. And yes, Zwift fixed the algorithm so land speed records aren’t broken anymore in banded Meetups. But the results above show that Keep Together mode still has plenty of room for improvement. Specifically, banded Club rides are moving too slowly, and speeds aren’t fluctuating realistically.
I’ll admit these tests are very limited in scope, and it’s possible that the banded experience is better in larger groups. But I also don’t think that’s the case, as banded rides I’ve taken part in have felt much too slow, and other Zwifters have said the same. Plus, the experience needs to be good in groups of just two riders, because it’s often just pairs of Zwifters who want to ride together!
Coming Up Next
Soon I’ll perform similar tests on Alpe du Zwift, to see how rubberbanding behaves on long climbs. I’ll also be testing rubberbanded Meetups to see if they behave differently than Club events. Stay tuned!
Questions or Comments?
Share below!
I rubber band one of my groups in our group ride and leave the other three not rubber banded. The group that is rubber banded sticks next to the riders they are around no matter how hard they go.
If the riders sprint at the start they will latch on to a faster group and once they latch on they can ride at very low power and be kept next to the group that is riding faster.
Essentially, once you lash onto a group that is not rubber banded you go at their pace.
There was a weird exception with long downhill segments like group rides through climb portals. Where the rubber banded group would descend slower than the people they were around, but that only happened once so maybe it was an anomaly.
I feel there is some weird scenarios going on with banded rides. I do a weekly hour banded ride with a club I’m in. When doing those rides I can happily do ~200w while most of the rest of the group averages less than 100w, and we will still only average ~15mph, depending on route, but 15mph is max average sometimes its less. But oddly enough the other week my Dad and I did a banded ride on PRL Full were we averaged ~180w and it felt like we were riding at the appropriate speeds we would normally ride at un banded. Looked back at Box Hill segments, and during the banded ride times were similar to unbranded rides at same power.
Just a weird observation I’ve experienced.
Hi, having led a weekly climb, I can tell you already : The group goes a tad slower than the faster ride, but not by much. People all have fake PR’s now because of this and well are getting shamed on Strava.
In that case, I wish it did an average and behaved close to what you saw on tempus. Although I don’t mind deleting my ride from Strava showing a 47m time up the alpe, not everyone feels that way and let’s face it. adz ventop are kind of landmarks for your timed performance and/or progression.
I also wish the climb portals could be in the route selection for events. For climbers EH
The Keep together feature for meetup rides has improved since last season and all riders in my meetup rides like how it works.
We tried running rides using the club event with keep together turned on but found the group rode much slower like something was holding us back. The keep together feature in club events does not work properly and we gave up on it and use only meetup rides for our bike club.
You’re saying the algorithm for Meetups behaves differently from Clubs?
That would be… unexpected if so. Maybe something else for me to test.
I’ve had the same experience as Andrew with the group rides I help organize. We’ve been using meetups for years and usually averaged 30-34kph, but we switched to Club events this December and now we max out at 25kph with the same group doing roughly the same level of effort.
I 100% believe that the rubber band behaves differently in Meetups vs. Club Events. I posted a question in the Zwift support forums and others definitely corroborated my belief.
hopefully someone at Zwift can look at this soon.
Absolutely true. Same experience in our club rides. Meetups until a couple months ago, then switched to club rides, average speed is off by about 3mph over 90 minutes. And this is comparing the same 5-7 riders that usually participate.
I get the same experience… rubber banded club rides are slower than rubber banded meetups
This. We have had the same experience in clubs vs meetups and even tested it to be sure. We only do rubber band in meetups now as a result.
Absolutely it behaves very differently on meetups vs club rides. AdZ is a perfect example of this.
I did a two man meetup on Sunday on Surrey Hills with rubber banding and averaged about 30kph for a Z2 flats/Z3 climbs workout on ERG and I think that was probably about right in terms of pace if we didn’t have keep together enabled
Going 36 km/h down radiotower with max 48 km/h while pedaling vs going 85 to 90 km/h down radiotower solo is my experience with a banded group between 6 to 17 people. The larger banded group rides with over 100 people are also noticeably nerfed on descents and the flat – but up the climbs like ADZ seem faster to me. Sprinting while banded makes you feel like you have ankle weights on while trying to run through mud.
Yes! Climbing is in hyper speed and sprinting is like doing so through molten lava!!
Thank you so much for doing this analysis. I’ve brought it up on the Zwift forums but no one seemed to be listening. Presume this won’t get much traction now with the employee layoffs but at least there is empirical evidence to support this!
Imagine somebody telling a programmer at Zwift HQ: please implement a rubberband feature so that groups stay together. Years and hundreds of bug reports later one can only think: man, you had one job to do…
Can you believe that over on Indievelo a single programmer is handling all features and there are no such issues at all?
I did a banded ride on the Shorelines and Summits route at the beginning of February. Speed on the flats were mind numbingly slow, but the climbs were ridiculously fast for the watts I was producing. (mostly Zone 2) I got a stupid PB on the radio tower doing 50watts less than my previous best. Any descents were also extremely slow compared to normal. I would estimate that the ride took 20-30 minutes longer than it would have unbanded.
I just don’t see the point of the feature and won’t take part in rides that use it. I don’t see the point in crawling around Zwift. When I putt in effort I want to see the result of my Avatar going faster rather than doing nothing.
Its a feature aimed at keeping the slow riders happy as they can ride with people faster than them without ever needing to improve their fitness.
I absolutely see the point of the feature. In fact, I would argue that rubberbanding is one of those cool things that is only possible in virtual cycling and not outdoors, so it’s worth talking about and getting right.
Rubberbanding offers the possibility of, for example, me riding hard while my dad, who isn’t as strong, rides with me at whatever pace he wants, even though he’s located across the country.
That’s pretty darn cool, IMO.
I agree with Eric. The rubberbanding feature allows a group of us friends to do weekly rides where some people are doing workouts and others are just chilling and bantering. I get to either ride easy and chat with my friends, or do a workout and have some help getting through longer intervals by reading the banter or hearing encouragement.
Great feature, IMO!
i rode up ventoux once at .5 wpk…. it was boring, and it was no use putting power down just really frustrating, not going anywhere.
hate it.
Eric, I hope you join us again on Tronathon as a test sample! I agree that the band really slows the group on flat portions in a disproportionate manner. I have to echo the comments on meet up banding different than club rides, at least in recent past. Rubberbanding is not for all but if the point of one’s ride is to build strength, consistency and socialize then its a fabulous tool.
Go Banditz – Most fun I have every had climbing……
Rubberband is my most hated feature of zwift. Luckily I don’t have to use it. Unfortunately I still have to pay for this nonsense feature.
Question… I’m sorta new to Zwift. If you are looking at Zwift Power
for up and coming Rides… How do you tell if the Ride is Banded?
There’s no way to filter events based on rubberbanding in ZwiftPower, that I know of.
ZwiftHacks is much more powerful for filtering. Including rubberbanding. Here are all the upcoming banded events: https://zwifthacks.com/app/events/?key=65ccf410c4071
What I’ve always wanted from rubberbanded rides is for it to be based on what % of your FTP you’re riding at. That way everyone can ride together by going at the same relative effort.
To my mind that would create the best sense of collaboration for a group ride.
Woah… that’s a cool idea!
I agree too. I have had one banded ride,…was well in front of the coach,…..at the head of the group, and was not sure is I was putting too much effort in! i would prefer %. of FTP
This is exactly what I like about banded group workouts!
I also noticed that if you fall off the back, say you lose connection and your power drops to 0, you can not catch back up to the pack, no matter how hard you peddle. I have fallen off the back and then peddled at 150 – 200% higher W/Kg than the highest output of any rider in the group and they kept pulling away, no matter hhard I peddled.
I have a memory of someone from zwift describing in an unofficial capacity how group workouts worked back when they were introduced. I believe they said that they crank up the wind or air resistance to keep everyone together. Something like that would seem to explain your findings. Solo riders go slower because of the increased resistance, meanwhile riders holding much lower wattage can stick inside the draft cone with very little watts but they don’t contribute to going any faster.
Thanks Tim. that would explain why I can’t catch up and continue to fall further behind the other riders even when I am putting out more power.
We noticed a long time ago that the rubber band works different in clubs vs meetups. Meetups using the rubber band aren’t artificially slowed down the same way clubs are, and it’s not close. It’s a very different implementation of the tool between the two.
I so wish this was a normal thing…………….please make it happen. I know you cant eric, but seeing you post it gives me hope for the future
But bike swapping! 🙂
You will undoubtedly have a different experience with AdZ. It’s supposedly a known issue they tried to fix unsuccessfully. I look forward to your report.
fwiw I hold a weekly banded meetup up AdZ that regularly has 20-40 riders and it is a very different experience than a banded club ride on the same route. The club’s Alpe time is regularly much faster than our meetup. Our attendees (for both) are in it for the social aspect, for earning their Trons and to help them climb better (and yes, climbing even in a banded ride is still a workout and truly does help non-climbers improve their fitness). We noticed when the band dynamic changed, we stay together much better than ever before on the meetup but depending on who’s pulling at the front, our AdZ times are usually between 70-80 minutes vs club times usually under 60. I would love to see banded segments automatically excluded from Strava personally but that may not be easy to do.