What’s happening with Zwift Racing Score?

November 22, 2024

LAST UPDATED November 21, 2024

Table of Contents

Zwift Racing Score (ZRS) went live as the de facto race categorization method on October 7, 2024. But that doesn’t mean Zwift has finished its work with ZRS! In fact, they’re working on lots of ZRS improvements in parallel, and it’s become rather difficult to keep track of what changes are being made, what’s in the works, and what Zwift is still considering for further changes down the road.

So I decided to create this page as an up-to-date tracker of Zwift Racing Score development. First we’ll list work Zwift is currently doing with ZRS, and below that you’ll see potential work Zwift is considering. Lastly, I’ll list the changes Zwift has completed.

Current ZRS Projects

New Seed Formula

My best guess for a launch date: mid-December 2024

Probably the biggest project currently underway, Zwift is working on a new seed formula algorithm that they hope will give riders a more accurate starting score.

The current seed formula is based on your 90-day power bests for 30 seconds and 10 minutes, but Zwift says, “We have two candidate formulas identified and are in the final stages of validation before implementing the change and rolling it out.” What does validation look like in this case? Lots of things, actually, but I do know Zwift is running numbers past their in-house data experts (peer review) and simulating how updated seed scores could change current score distributions (impact analysis).

While they aren’t saying what power numbers the new formulas are based on, I would expect them to use intervals longer than 30 seconds, since that metric has been problematic. Plus, Zwift said, “We found that while 30 seconds is still a solid metric, we can do an even better job at seeding by factoring in alternative data points.”

Race Requirement Lowered To 1 Activity

My best guess for a launch date: week of November 25, 2024

Zwift added an activity requirement in late September, so riders had to have at least three 10-minute activities recorded in the last 90 days before racing a scored event. This was done to try and get a more accurate seed score for riders before placing them in a race category, so hopefully riders wouldn’t be under-seeded and blow up lower-category groups.

Zwift is planning to reduce this requirement to just one 10-minute activity because they “received feedback that the barriers to race are too high.”

The obvious concern with this change is that it will increase the number of under-seeded racers. I spoke with Zwift about this, and they said that once they implement changes to look at riders’ history further back than 90 days (see Potential ZRS Changes below) this should fix a lot of those issues. But for now, they think making this change is, on balance, the best move to improve the Zwift racing experience.

Requiring a Minimum Effort (Anti-Tanking)

Zwift says “We anticipate this mechanism to kick in before the end of November.“

It appears as if a small minority of racers have been purposely “tanking” their scores by entering races and essentially soft-pedaling to get a bad result and lower their ZRS, so Zwift is working to implement changes to detect and stop this sort of intentional score manipulation.

I asked Zwift for details on how they’re doing this, but they (understandably) didn’t want to share specifics. What they did say was their system is very similar to what ZwiftRacing.app uses, which means it looks at your past performance history, and if your current race effort isn’t meeting a certain threshold compared to that past performance, the activity is flagged and your score will not drop as a result of your finishing position.

Side note: as you may know, Tim Hanson over at ZR.app is working as a consultant for Zwift on the ZRS project, so it’s no surprise that parts of ZRS would look like parts of ZR.app, which has developed a very solid reputation in the Zwift racing community.

Tim told me that in his experience, around 1% of race activities appeared to involve intentional score tanking. Zwift therefore tuned their detection parameters with that 1% goal in mind.

Zwift says, “This took slightly longer than anticipated to develop, but we wanted to take the time to ensure the mechanism catches instances of intentional score tanking as accurately as possible.”

Event Category Ranges

My best guess for a launch date: January 2025

Zwift is looking at “revising our default event category ranges to better align to the score distributions after the seed formula updates.” That is, once they modify the seed formula (above), they anticipate that the distribution of riders’ scores will change, and they may need to change category ranges to better balance group sizes and ability ranges.

“We’ll also be taking this as an opportunity to find ways to make the subgroup ranges smaller, and therefore more competitive,” Zwift says. “How can they do that,” you may ask, “When the system is currently limited to 5 categories for any given event?”

Zwift tells me they’re seriously considering breaking elite riders into their own events, which would free up a subgroup on the current events. Anyone would be allowed to enter the elite events, but it would be clear these events are where the strongest racers go.

So one particular race event may become two and look something like this (numbers entirely made up by me):

Snazzy Race Event

0-250
250-350
350-450
450-550
550-650

Snazzy Race Event (Elite Version)

All racing scores allowed

One positive of this approach is that we’ll effectively be adding another subgroup for events, making competition tighter in the lower categories. This would also let Zwift consolidate their elite race events, perhaps only holding one every two hours instead of hourly, to increase the number of participants. Lastly, this approach is doable right now, without making changes to Zwift’s categorization systems or pen artwork.

But longer term, Zwift really needs to modify their category system to allow for more groupings. Imagine the flexibility race organizers could have if there were up to 10 groups allowed, instead of 5. (Right now, the only way to get 10 groups is to hold two separate events – and that’s just confusing and kludgy.) If Zwift could expand their pen limit it would open up event possibilities, including dynamic pen assignment, which could really add some interesting layers to Zwift races.

Category Enforcement When Joining

Zwift says, “This functionality is expected to start appearing with events in January.”

Right now, Zwift’s system only validates your signup to a race when you sign up. It doesn’t double-check if you are still in the right category when you enter the actual start pens.

This can lead to racers being underseeded if they sign up for races well in advance while their score is low.

This will change soon, though. Zwift says they will be validating your category when you enter the start pens, and this validation will occur in all race events.

Potential ZRS Projects

The following changes are being discussed by Zwift staff, but are not currently being worked on:

Improvements to the volatility of score movement at lower ranges (est Dec 2024). Scores in the lower ranges aren’t moving as quickly as Zwift would like to see, so they’re looking at ways to change that.
Looking further back than 90 days for the seed score (est Jan 2025). This is an important change in regards to seeding riders accurately and thus reducing cases of underseeding, which negatively impacts race experience in the lower categories.
Arrow indicators when min effort mechanism kicks in (est Feb 2025)
A historical view of how your score has changed over time. Zwift said in this post “We are planning to introduce a view for viewing your score history. We’re already tracking full history in our backend, it’s just a matter of implementing a view of this.”
Dynamic pens: dynamically grouping riders based on signups to automatically provide for the most competitive and race groups.

Completed ZRS Projects

The following changes have all been completed since ZRS originally launched under Zwift Labs in June 2024.

Decay Turned Off (October 29, 2024): “The original intention with decay was to account for decays in fitness after going an extended period of time without riding. After evaluating the functionality and reviewing feedback, we have decided to disable decay for now since it doesn’t seem to be providing the intended value. We may turn this back on later after making some improvements to the mechanism.” People will see small increases in their scores once it is turned off.”
Podium Bonuses: The top 3 finishers in each scored race are now receiving a podium bonus meant to help move racers up a category faster if they are regularly winning.
Finalized Subgroup Score Ranges: Zwift has defined the score ranges they will use for Zwift-owned races and recommend for community organizers. (For more information, see this forum topic.)
Faster Score Calculation: Scores are calculated and adjusted as each racer crosses the finish line, instead of being finalized after 12 hours to account for DNF’s. This will eliminate issues where individual scores would drop when checking the day after a race.
3×10-Minute Activity Requirement: Riders must now have at least three 10+ minute activities recorded in the last 90 days in order to race a scored event. This helps ensure an accurate seed score, to improve initial subgroup placement.
ZwiftPower Score Range Filters: ZwiftPower.com will be updated so users can continue tracking General Classification (GC) standings after event series like the Zwift World Series move to score-based subgroups.
Bug Fix for Stuck Low Scores: Zwift says they’ve “fixed an issue where scores that drop too low get stuck with low values even after winning several races.”
New indicator icons in race results to show if you hit your floor value or had a major jump based on setting a new 30s to 600s best (Aug 22, 2024)
Score volatility fix: “We will also be fixing an issue that prevented score from moving as quickly as they should when a new 90-day power best/floor is established”
Fixing web results so up/down arrows display correctly
Slowing the rate at which your ZRS decays (July 8, 2024)
Showing your updated score when you return to the game homescreen after a race
Changing ZRS-based bands in Zwift-owned events to use different score ranges: these score ranges have been modified several times as ZRS has developed over the past months.