ZRL Categories: Watts the Solution

Over the past three weeks, we’ve dug into why the current ZRL Category system disadvantages women and lighter riders. I started by diving into Team OWL’s first ZRL experience and uncovered the shortcomings of using w/kg as a measure. Next, I examined how that flaw affects the ZRL category upgrade system. Finally, I explored how combined racing in ZRL has a built-in safeguard—one that’s missing from women’s-only ZRL races.

Thanks to everyone who joined the conversation on social media—your input has been incredible! The big question everyone keeps asking is: What’s the solution? Over the next three weeks, we’ll explore three possible fixes.

First up, the most straightforward one: Watts the Solution.

Yes—literally switching ZRL categories from being based on w/kg to being based on watts.

It’s not flashy. But it works.

Why the Current ZRL System Isn’t Fair

Remember the data from our first article? A 50 kg rider at 2.5 w/kg puts out 125 watts, while a 69.3 kg rider at 2.5 w/kg produces 173 watts. Same race category—yet the lighter rider is generating 48 fewer watts. That’s just physics.

And here’s where w/kg categories turn unfair: because the ratio looks equal, lighter riders get placed in fields with competitors who produce far more absolute power. You end up racing athletes who can push significantly more watts.

That’s not a fair competition. It’s a penalty for being a lighter weight rider.

But here’s the thing: we don’t have to live with it. There’s a solution sitting right in front of us, and it’s beautifully simple. Switch ZRL categories from w/kg to absolute watts.

Why Watts-Based Categories Work Better

Switch to watts? Now you’re racing people producing similar total power. That’s a fair fight.

Let’s say ZRL creates divisions based on absolute wattage based on a rider’s zFTP:

• 275+ watts
• 215-274 watts
• 155-214 watts
• 100-154 watts
• <100 watts

(These numbers are illustrative—ZRL would refine the divisions based on their actual data for women’s only races.)

	zFTP	Weight	w/kg	CAT	Age
Her Data	165w	69.3kg	2.38w/kg	D	Vet 40-49
My Data	125w	50kg	2.5w/kg	D	66

Now the same two riders are split into different categories:

• Her division C: 165 watts → 155-214 watts division
• My division: 125 watts → 100-154 watts division

In each race division, women produce similar power. Lighter riders aren’t constantly outgunned by bigger riders with “equal” w/kg. You’re competing against peers at your actual raw power output.

New Division. New Playing Field.

Let’s see how this plays out. Since I’m now racing in a completely different division from the rider I originally competed against, I’ll look at data from women in the same race on ZwiftPower, with similar raw wattage for comparison.

There were 61 women in that event, so I started by sorting the finishers by watts. Try this sometime—it’s a simple way to spot a clear trend: riders who weigh more often finish higher. It’s the basic physics of cycling power-to-weight at work.

Next I divided the riders into two divisions: 155-214 and 100-154. In the first division only 3 riders placed lower than 40th overall, and only 2 of them weighed under 60 kg (57 kg and 58.1 kg). All finished within 07:27 from one another. That’s what a fair race looks like.

In the 100-154 watt division, 6 riders still cracked the top 40 overall—and only two weighed over 60 kg. They all finished within 14:56 of each other, a much wider spread than the upper division’s 7:27.

Why the gap? It’s a pattern I’ve seen with Team OWL’s “pocket rockets”—and other featherweight riders who train hard. Lighter riders must sustain much higher w/kg ratios (often 3+ w/kg) to compete, since their lower absolute power demands exceptional relative output just to hang on.

One caveat: for my analysis to be truly accurate, I’d need each rider’s zFTP. Instead, for the sake of practicality, I used their average power from this specific race, which usually comes reasonably close.

Closer to the Pro Model

This kind of category division—based on raw watts rather than w/kg—actually mirrors how professional women’s cycling teams work. To race at that level, riders must hit a certain absolute power output to even make the roster. Teams build lineups around these power benchmarks, ensuring every athlete can contribute the necessary strength to the group’s overall performance.

Of course, raw watts still vary among pros. Just look at Marlen Reusser and Gaia Realini—two riders with very different body types and roles. Reusser, a powerhouse time‑trialist, produces enormous raw wattage, while Realini, a climbing specialist, delivers a much higher power‑to‑weight ratio thanks to her lighter frame. They excel in distinct disciplines—but both must meet a baseline level of power output to compete effectively at the WorldTour level.

In that sense, moving to watt‑based categories aligns amateur racing more closely with the realities of professional cycling: success depends not just on relative fitness (w/kg), but on the absolute power required to stay in the race (watts).

What This Means for ZRL Women’ Racing

We’ve all seen women riders get discouraged—thinking they’re “not strong enough” for their category when, in reality, the system is stacked against them. Watts‑based categories change that.

Right now, if your w/kg looks “equal” to heavier riders, you’re grouped together—but you’re producing far less actual power. Frustration sets in. You start to question whether you belong.

Switching to watts fixes that:

• You race against people who produce similar power.
• You know exactly where you belong, based on what your body actually delivers—not a misleading ratio.

That’s the difference. That’s fairness. That’s empowerment.

The Objection (And Why It Misses the Point)

“But won’t heavier riders dominate in watts‑based categories?”

Not in the way that matters. In watts categories, heavier riders race other riders producing similar watts. They’re competing with power peers, not against lighter riders anymore.

And that’s the real advantage: watts categories are honest. They recognize that lighter riders naturally have a lower power ceiling. Instead of pretending w/kg makes everyone equal, watts‑based divisions respect those physiological differences and create fairer, more balanced racing.

What’s Next

Switching ZRL categories from w/kg to watts is an obvious fix. It immediately levels the field for lighter riders, it’s simple to implement, and the data supports it.

But there’s more to explore. Next week, we’ll dive into something even more refined—something Zwift has already built: the ZRS (Zwift Racing Score). Could it be an even better path to fair categorization in ZRL racing?
Maybe. Maybe not.

Stay tuned.

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Want to dig deeper into the physics yourself? Head to Best Bike Split and run these scenarios. Compare riders at the same w/kg but different weights. See the power gaps for yourself. The data doesn’t lie—and once you see it, you can’t unsee it.

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