August 20, 2020

LAST UPDATED August 31, 2020

Welcome back for the second installment of “How to Become a Top Category Zwift Racer” series! If you missed the article on Cat B, you can read it here.

Before I launch into findings, I have one request: some of the high ranked people in Cat C are very young, like under 12, so let’s be gentle in the comments. They are racing in the system provided.

If you don’t know about ZwiftPower and how it ranks racers, click on C in the standings report. Based on your feedback from the last article, I expanded the dataset and used the top 60 Cat C racers as a basis for analysis below. Only race data is considered; group rides and tours were excluded.

Based on the data, if you’re looking to move into the top 20 cat C positions, try to emulate the following:

Race Experience: These people race a lot and get very good at it. Zwift is a skill.
Ways to Win: There are more ways to win in Cat C than Cat B. It looks like you can win high-quality races with long climbs, breakaways, and sprints.
Draft Masters: While these riders can produce good power, they seem excellent at sitting in the draft.
High 15-Second Sprint Power: 8.7 W/kg
Near Top of Category 20-Minute Power: All of the riders in the analysis are capable of riding at or near the top of Category C power. Read “20-Minute Power” below for a more nuanced view.
Be Light: Being around 50 kg can help you exceed category W/kg limits without being forced to upgrade to B.
Race against good competition: Top C’s are doing a lot of series races and high-quality C races. Surprisingly, most of these people race in Cat C regularly.

If you’re curious about the specific data I used, check out all the data details at the end of the article. Otherwise, let’s jump into the number details.

The Numbers Breakdown

As a reminder, Cat C is defined as 95% of your 20-minute power being between 2.5 – 3.2 W/kg and above 150 watts.

I want to mention that there are riders in this group that average 30-50% higher than allowed by Category C limits. These riders skew the data pretty heavily in some areas, much more than in the Cat B analysis. I will try to break things down in a way that makes sense by analyzing the entire group while sometimes pulling out the outliers. I also broke this data into tiers of riders based on rank to see how things changed.

Let’s get moving. Here is the data table:

Raw 20-Minute Power

To get into the top 20 you have to be able to hold around 3.2 W/kg for 20 minutes. Why does the data above say 3.4? It is skewed by a few people who are significantly higher than 3.2 W/kg as shown in the graph. If you remove the riders averaging over category w/kg the average for the top Cat C riders is 3.1 W/kg.

As you can see in the chart, there is no real difference in the 20-minute power between the top 20 Cat C riders and the 21 – 60th ranked riders.

If we remember that the actual FTP ZwiftPower uses is 95% of this 20-minute power for their calculations (thanks to one of the commenters on the previous article for pointing this out), that means the ZwiftPower average for their 20-Minute power is only 2.95 W/kg. This seems to indicate these riders are very good at riding in the draft and conserving energy.

5-Minute Power

You need to be able to hang with this group up the hills. About 3.7 W/kg is the average for the group. The light riders average higher (obviously).

Head down to the Percent of 20-Minute Power section for more detail on 5-Minute Power.

1-Minute Power

Because many of these riders weigh more, many of them are able to produce exceptional raw power over one minute, between 400 to 525 Watts. Their ZwiftPower profiles show them in the 80-95th percentile of all Zwift riders (I don’t have race-only data to confirm those percentiles are applicable to races). As Eric Schlange pointed out in this article, the higher your raw power, the faster you go given the exact same W/kg. I would be interested to see how that plays out in a race.

A few takeaways from the above graphs:

The very high end of Cat C has 1-minute W/kg power in line with very good Cat B racers (between 6 – 7.0 W/kg)
The 1-Minute Raw Wattage for these riders averages 402 Watts with the median being 426 Watts. So if you are an adult, you will need to average at least 400 Watts to keep up over the last minute.

15-Second Power

Similar to the Cat B findings, it appears that a combination of 1-minute and 15-second power is the key. You have to be good at both. As you can see in the graph, you need to be able to average at least 7.5 W/kg, and realistically 9 W/kg to get into this upper echelon of C category racers.

Percentage of 20-Minute Power (Comparing C to B Riders)

As I was running this data I kept wondering “How does this compare to Cat B”? So I decided to break the data down as a percentage of 20-Minute Power to see how the two categories stacked up. Below is what I discovered:

5-Minute Percentage: There is only a slight difference (1.8%) between the two percentages here, meaning that Cat B puts out about 1.8% higher wattage when compared to their 20-Minute Power for a race. Is this a meaningful difference? I don’t know. I think it is indicative of a challenge when moving to Cat B. Not only do the riders in Cat B have a higher 20-minute power, but they are also capable of going up a hill at a higher percentage of that power. As I am sure we have all experienced, even a 5-6 watt increase can be the difference in hanging with the group and the thread breaking with 20 seconds left up a long hill.
1-Minute Percentage: The difference is larger here, 6.9%, between the two groups. What this says to me is that there is a bigger wind up for the finishes of the Cat B races than the Cat C.
15-Second Percentage: Here we have a 10.5% difference, meaning the sprint is much faster in a Cat B race relative to the average 20-Minute power.
I would have expected all three of these numbers to be comparable, I don’t see an obvious reason Cat B would put out a higher % relative to 20-minute power than Cat C. It may be that the races are just very different, where Cat C are broken apart and Cat B stay together in bunches, so the people at the top in Cat B are the best sprinters. Even then I would have expected Cat C to put out a higher % on the 5-Minute power to create those breakaways.
It may be possible that as riders get better their shorter power numbers rise faster than their 20-Minute power.

Heart Rate (HR) vs. Percentage of Max Heart Rate

Many of the comments on my last article centered around the topic of “sandbagging”, or people not racing as hard as they can. The DIRT team had a thread going discussing the percent of max HR as a measure of effort, so I took a look for Cat C.

Looking at the graph, most riders are in a narrow band between 80 – 90% of their Max Heart Rate. This was taken as the maximum HR value I saw in all of their race data and seems totally reasonable!

I know what you are thinking: “Rick, this data means nothing without knowing the raw numbers for average heart rate (Average HR). Don’t you know anything?” Well, here you go! See the “Average HR vs. Rider Rank” chart.

I really made every attempt to look smart here by summarizing good takeaways from this data, but after writing this paragraph 5 times, I just don’t think there is much to talk about…it looks pretty normal. I did want to share the data, however, to help answer questions around these data points.

Races Per Week

Same as Cat B…If you want to get a good rank you have to race a lot. Don’t underestimate the power of learning how to race well and the luck of needing an aero to place high enough to get that race ranking.

The average is 1.9 races per week. But check out that person racing over 6 times a week!

Podium Percentage

This was one of the more surprising takeaways. I anticipated that most of these people would be amassing points through racing Cat B, but instead 50 of the 60 race primarily in Cat C. As you can see from the graph, they are cleaning up. The average podium percentage for this group is 59.2% which is incredible. It continues to lend to the theory about Cat C races getting broken up more before the sprint, so getting on the podium is more a matter of strength than position / luck.

Other Tidbits

The racers are clustered around 50 and 90 kg
- The 50kg group mostly made up of young athletes and women
- The 90kg group is perplexing; I don’t know why there is a cluster here. One of the commenters on the Cat B article mentioned that they thought Cat C would be heavier than Cat B, so kudos to him / her!
A lot of these racers appear to be very new to Zwift, or at least ZwiftPower. It appears as though C is a common starting category, and I would guess there is more turnover in these rankings than any of the other categories
50 of the 60 riders race primarily in Cat C. Five race in B/C races, one races exclusively in Cat B, two race in A/B, and one races mostly in Women Only events
At a minimum, 3 of the 60 riders are women
5 of the 60 riders have fake names (this is a lower percentage than Cat B)
2 of the riders were verified by ZADA at some point
8 of the 60 riders are Under 20, 2 are between 23 – 29, 15 are between 30 – 39, 21 are between 40 – 49, 8 are over 50 and 5 are over 60. 1 person either refuses to be defined by ages or is immortal
33 of the people are from Europe, 17 are from North America, 6 are from Oceana and 4 are from Asia
A lot of the racers participate in Time Trials (ITT and TTT) as well as racing series. There didn’t seem to be a targeted race type like in Cat B.
The racers were DQ’ed 1.9% of the time due to UPG/HR/DQ

The Data Details

Data Source: ZwiftPower
Data Curation: Manually downloaded. I would love to pull more data and do other analyses (see other articles I’m planning at the end) but I haven’t found an API to download all of the data from ZwiftPower. (Guys who run ZwiftPower – hit me up.)
Data Filter(s): Past 90 days of racing from the Top 20 category C racers as of August 4th. When you look at the rider profiles you will see higher power than what is shown below because the data I used is only from races where the rider achieved a rank of under 420 for the race ranking. Our goal is to identify how to become a top Category C racer in Zwift, not to see what everyone’s max wattage is during a 2.0 W/kg group ride with a sprint in the middle. Also, cutting off at 420 is arbitrary. Looking at the best five races from the racers between 50th and 60th it seemed appropriate.
Analysis Tool(s): Google Sheets and Excel.

Next Articles and Projects:

Below are additional data-focused articles I plan to write, also based on data from ZwiftPower:

Cat A+ is next, then Cat A
Women Specific article – I’m not sure of format and Categories
What it takes to win a Zwift race
Zwift Rankings and Category Improvements
How to Race like a Pro – This is a teaser for another project I’m working on. Details to come soon!

A huge thank you to everyone who read the last article and provided feedback. I really appreciated every single comment and tried my best to respond to everyone.

Also – thanks to my amazing wife for helping with the edits.

Ideas and Comments

Let me know your thoughts on this one and ideas for future articles in the comments below! I am particularly interested to hear your thoughts on whether my conclusions align with what actually works for real Cat C racers. I promise to respond to your comment (unless you say something mean about me, in which case I will immediately write a pithy response, followed by me deleting said pithy response, followed by me responding with “thanks for reading”, written with no exclamation point and no capitals because that way you know I am mad at you).

Good Luck and Ride On!