We’ve recently completed an expansion of our ZIMetrics data, and are now using it to show precise metrics for all bike frames, wheelsets, and routes in Zwift.
On top of that, we’ve just launched detailed homepages for every frame and wheelset in the game! (See them by selecting a frame from our master frames list, or a wheelset from our master wheels list). While we’re still entering data and images for some frames and wheels, the basic info is in place and quite useful.
If you have questions about how ZIMetrics work, read on for details.
Route Ratings
Each route also has an objective “Rating” score between 0 and 100. This is simply a normalized version of the time estimates (more on those below). For example, if ZIMetrics estimates that a route will take 40 minutes to complete, that means it will have half the rating of a route estimated at 80 minutes.
Yes, it’s not a perfect metric. But I’m not sure such a metric exists. The ZIMetric route rating is a simple way to rank routes against each other.
The current highest-rated (that is, the toughest) route – London’s “The PRL Full” – is rated at 100. If a tougher route gets released all scores will automatically be recalibrated based on the new maximum.
Route Time Estimates
First, let’s acknowledge that there’s no way to estimate a perfectly accurate completion time on Zwift, unless it’s a TT race and you’re perfectly following a particular “power plan” Ã la BestBikeSplit.
Our goal with these time estimates is to predict how long it would take a semi-experienced rider, riding efficiently in a group, to finish one lap of the course, including any lead-in. The algorithm assumes you’re a 75kg, 183cm rider drafting on the flats, on a decently fast bike, and pushing harder on climbs than on flats and descents.
Basically, the algorithm is based on a typical Zwift group ride or race situation.
Of course, draft conditions vary widely, as do rider height/weight, choice of bike, and power variability. To keep it simple and avoid requiring people to enter height, bike choice, etc, we made certain assumptions, and it doesn’t seem we lost much accuracy in doing so. In our backtesting, we found that the ZIMetrics estimates are almost always within 3% of the actual completion time. That’s certainly close enough for our purposes.
Bike Frame Performance Ratings
One common complaint from Zwifters (at least, the nerdier racers) is that Zwift’s 4-star rating system for aero and weight isn’t granular enough. That is, two bikes could both have the same rating, but perform quite differently.
With our performance ratings for bikes and wheels, we’re bringing a much higher level of precision to measuring the aero and weight characteristics of each piece of in-game equipment. Instead of 4 stars based on the frame/wheel’s in-game CdA and weight settings, we’re using a 0 to 100 scale based on the frame/wheel’s actual in-game performance.
See frame ratings by clicking a frame on our master list >
The metrics are quite straightforward for road bikes: an aero rating of 100 means it’s the most aero road frame in Zwift, while a rating of 0 means it falls below the performance of our baseline road frame, the Zwift Carbon.
There are a few details worth clarifying when it comes to frame metrics:
- Stage 5: The performance metrics assume you’re using the max-upgraded version of the frame, not the stage 0 version. This is important to note because, while most road frames maintain the same performance gaps between each other from stage 0 to 5, a few road frames – notably the Specialized Aethos S-Works – follows a different upgrade path, and thus becomes a much better climber when fully upgraded.
- TT Bikes: Ratings for TT frames are based on the performance of other TT frames. So a rating of 100 means it’s the fastest TT frame in Zwift, while a rating of 0 means it has the same or worse performance than our baseline TT frame, the Zwift TT.
- Example: If the fastest TT frame has an hour time gap of 93.4, while our baseline Zwift TT has an hour time gap of 45.6 seconds, a frame directly between those two times (69.5 seconds) would earn an aero rating of 50/100.
- Gravel Bikes: Ratings for gravel bikes work similarly to TT bikes – they’re based on the performance of other gravel bikes, not the performance of other road bikes.
- Halo Bikes: Halo bikes are a bit tricky, because they include a wheelset, so you can’t exactly separate the performance of the frame from the wheels like you can with other bikes. Therefore, we compare Halo Bikes to the fastest road bike frame+wheel combos in the game. And even still, the aero rating is over 100, because fully-upgraded Halo Bikes are faster than any road frame+wheel combo (see Specialized Project 74 as an example).
- The Pinarello Espada is an exception to this, since it’s a Halo TT Bike, not a road bike. For the Halo TT Bikes, we compare the bike to the fastest TT frame+wheel combo in game.
Wheelset Performance Ratings
We have the same sort of 0 to 100 ratings now in place for all wheelsets in Zwift (see example above). Wheel ratings have a few details worth noting as well:
- TT and Road Ratings: Road wheels include aero and climb ratings for use on road bikes as well as TT bikes (see screenshot above). This is because some wheelsets – particularly disc wheelsets – perform differently on TT frames than road frames, because Zwift sets them up with a CdA bonus on TT frames to discourage their use on road bikes and encourage their use on TT bikes.
- Gravel Ratings: Since Gravel wheels can only be used on gravel frames, we’re only comparing gravel wheels to each other for our metrics. So a gravel wheelset with an aero rating of 100/100 means it’s the most aero gravel wheelset available, but that doesn’t mean it’s as aero as a 100/100 road wheelset.
See wheel ratings by clicking a wheelset on our master list >
Questions or comments?
Hopefully Zwifters will find these metrics useful as they research routes to ride, and which virtual bike frame and wheelset to use for those rides.
Got questions or comments? Share below!
