Speed Tests: Rubberbanding (Keep Everyone Together) Mode on Climbs in Zwift Club Events

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!

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’ve been running tests to find out what speeds rubberbanded riders reach at different power levels, in different event setups. For science!

The core question I want to answer is: Do rubberbanded speeds make sense? Are they too slow, too fast, or some strange mix of both?

My first tests were on flat ground in a banded Club Event. Then I did more flat tests, but this time using a banded Meetup. Today, we’re digging into our first banded climb tests, using a banded Club Event.

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 Alpe du Zwift climb segment since it’s steep and long enough to be a good representation of climb performance.

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.

Observations

The first thing that stands out here is how illogical the results are. Why would two banded riders holding 300W be 7 minutes slower than one rider holding 300W banded to a rider holding 75W?

This pattern repeats itself, too. When two riders match wattage, they turn in a much slower time than when the wattages are unmatched, even though the stronger rider’s wattage is the same in both tests.

That’s not to say the matched wattage times are particularly slow, though. They just seem slow because the unmatched wattage test times are way too fast.

For example: a solo rider holding 300W climbs the Alpe in 49:28. But a banded group with one rider holding 300W and the other holding 75W climbs the Alpe in 40:11!

The other odd thing is how the pair times don’t change as the weaker rider’s power decreases. (This same phenomenon was observed in our flat tests.) 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 how a solo rider in a rubberbanded Club event performs compared to the paired riders above. So I created an event with “Keep Together” enabled, but only had one rider join. Here are the results:

Compare those numbers above to free ride times with a solo rider (which should, in theory, be the same):

Observations

First, notice that when there is just one rider in the rubberbanded event, their speeds are much slower than they would be when free riding. That’s goofy. The speed difference between a solo rider in a banded event vs free riding isn’t as dramatic on the Alpe as it was in our flat tests, but there is still a significant difference.

Also, notice how the solo tests all came in significantly slower than the paired rider tests, even though logically that wouldn’t happen.

Concluding Thoughts

Simply put, Keep Together mode is broken up Alpe du Zwift. Zwift supposedly slowed banded group speeds on climbs in their version 1.52 update, but based on the results above, speeds are still too high!

I’d love to see rubberbanding improved so it’s a more realistic experience, but we also think Zwift should consider flagging all banded rides as “Gamified” when uploading to Strava, so we don’t set new segment PRs thanks to unrealistically high speeds in banded rides. Holoreplay and other in-game PR data also should not be saved for banded events, and times should not show on leaderboards outside of the event itself.

Coming Up Next

Soon, I’ll perform similar tests using banded Meetups, to see if/how Meetup banding behaves differently from Club Event banding. Stay tuned!

Questions or Comments?

Share below!

The new Zwift Big Spin series has just kicked off, and many riders are joining the events in hopes of spinning and winning limited-time novelty unlocks. One of the most popular is the “Zwift Tri Spoke // Disc Wheel”. It’s an eye-catching wheelset and the first tri spoke in game, so many Zwifters are riding extra Big Spin events just for these wheels!

Unfortunately, the Tri Spoke was misconfigured when it first launched, meaning it turned in super-slow times more on par with gravel bikes than road bikes (see original speed test results). Zwift fixed this issue quickly, though, rolling out the fix in the version 1.61 update that was released this week.

Once we downloaded the update, we went to work running fresh tests. Zwift has indeed reconfigured the wheels, but the star ratings didn’t change: they are still rated 3 stars for aero and 1 for weight. This illustrates how non-granular Zwift’s star ratings actually are. They simply aren’t precise enough to communicate actual in-game performance in a useful way for picky racers, so we ran the wheels through our battery of speed tests.

Here’s everything you need to know about the updated Tri Spoke /Disc Wheel’s performance in Zwift.

Aero (Flat/Rolling) Performance

Tri spoke + disc wheels are commonly seen on TT setups because they’re fast. So we expected Zwift’s new Tri Spoke to be pretty zippy on the flats.

The updated wheels aren’t anything to write home about, though. Despite looking quite aero, especially with that rear disc, the wheels turn in a test time of 50:53.5 on our test course, which is two laps of Tempus Fugit totaling 34.6km.

This is almost 3 minutes faster than the old misconfigured wheels (so that’s a big improvement), but also 19.5s slower than the 808/Disc wheelset, which is the slower of the disc wheelsets. The aero performance of the updated Tri Spoke is now within 1 seconds of the ENVE SES 6.7, Zipp 404, and Zipp 353 NSW wheels… all wheels that are better all-arounders than aero performers.

Climb Performance

Given the Tri Spoke’s 1-star weight rating and mid-tier aero performance, we didn’t expect great things on our Alpe test. We got what we expected.

The Tri Spoke // Disc Wheel turns in an Alpe climb time of 49:47, which is almost 2 minutes faster than the misconfigured Tri Spoke, but still quite slow. These are still the slowest climbing wheels in game, 8s slower up the Alpe than the next slowest wheelset (Zipp 808/Disc combo) and 33s slower than the best climbing wheels (the Lightweight Meilenstein and Roval Alpinist CLX.)

Note: all test results above are from a 75kg, 183cm rider holding 300W steady using the Zwift Aero frame.

Conclusions

The original Tri Spoke wheels were so slow that riders could easily sense their poor performance in races or RoboPacer riders. The updated wheels are much faster, so riders using them probably won’t notice a performance hit compared to other rigs.

That said, there is indeed a performance hit! The aero performance of these wheels puts them mid-pack, and they’re the Lanterne Rouge in climb performance.

These wheels are now useable for relaxed rides, but we can’t recommend them for racing.

Questions or Comments?

Share below!