I’m a long time Zwifter, outdoor cyclist, and 133 pounder. I’m sure other light riders on Zwift have been getting punished on flats and descents as I have. We typically have need a 20% higher watts/kg (4 w/kg) on a flat to stay even with a 175 lb rider (3.4 w/kg). On climbs, we manage to hold even for similar w/kg. The physics here seems slightly disjointed to what I experience outside with other riders I’m familiar with. I typically drop them on climbs there.
There is no scenario in Zwift where a light rider has an advantage of any kind. The best we can hope for is a 10% graded long climb (which rarely exists in races) and here we simply match the performance of a larger rider w/similar w/kg.
But I trust the brilliant minds at Zwift and have to assume their physics calculations are accurate, so I continue to take my licking there and enjoy it. Ok, so here’s my dilemma and I consider this a category placement bug. We know light riders require a 10-20% higher w/kg with med-heavy riders, and I accept that phenomenon. But why is that not being considered when categorizing us? We’re being thrust into higher racing categories where we’re lucky to finish in the top 75%. This is being strictly based on w/kg and not on physics showing my 3.4 w/kg is actually 20% lesser than a heavier rider’s 3.4 w/kg. Why should I be considered a B racer and not a C racer? It’s demoralizing. Look at race results and w/kg and you’ll regularly notice light riders with higher w/kg finishing much further back in the results. Please adjust your category rules to strongly consider rider weight and not just w/kg.
BTW, I’m also a long-time Zwift fan and supporter. Keep up the amazing work!
The easiest way to improve your performance on Zwift is to weight dope - to reduce your weight to give an advantage without increasing your power. If you increase your weight in Zwift you will find that you perform much more poorly at the same power. Try shifting your weight to 100kg and doing a hilly race for instance.
On climbs in particular light riders have to put in a lot less raw power than a heavier rider, which is a big advantage since most breaks in Zwift are on a hill.
So - On climbs w/kg rules and lighter riders can shoot up quickly without a massive power increase, on flats it’s more shifted towards pure watts where a big rider pushing large watts tends to do a lot better as in real life.
Aaron, thanks for sharing your thoughts. I understand and mostly agree with your thoughts. I do agree that light riders compete better on climbs than they do on flats, but even there, I wouldn’t say they have an advantage when comparing w/kg. It’s more like we’re equal. I think ZwiftInsider published an article on this a couple years back. In the outside world, it seems there’s a more obvious advantage. Not trying to be at all disrespectful but can I assume you weigh 160 or more? I think you have to be a light rider to truly feel what is constantly a challenge in Zwift.
I think that’s because you’re not comparing power at that point, you’re comparing power to weight ratio in both cases, which is not necessarily the right thing to compare on flats. From what I’ve read in the past I think you’d want to compare a combination of power and aero on flats rather than focus on W/kg. In Zwift they have to make some assumptions on aero which maybe they get wrong - not sure about that.
So a 50k rider doing 5w/kg on flats (250W) would probably not be able to keep up with a 100kg rider sustaining 5W/kg (which is waay more power at 500W).
Yep, totally agree there. I regularly have higher w/kg while DRAFTING behind larger riders on flats. My point in this topic is that when Zwift if placing us in categories, they’re basing it on w/kg… which like you and I say, is the wrong thing to focus purely on. So, I can’t compete with a large rider doing 3.2 in a C race while I’m at 3.4, yet I get upgraded to B category to suffer while they remain in C to consistently finish well. I have several light teammates (women and men) suffering the same fate.
Ah, I see. I don’t like w/kg categories either. Without any ranking system I tend to favour a compound score seeding (which is a combination of your 5min power multiplied by your weight) as a starting point for categorization. zwiftracingapp does this which works pretty well (they modified the formula a bit to do better at both the light and heavy sections).
Definitely true that lighter riders have a disadvantage on the flats and get upgraded faster. I am not even that light and I seek out the hilly races. Plus those races are a lot more fun because it’s not just cruising to a sprint where you’ll get overpowered. This excludes most of the really big races put on by Zwift HQ but there are still quite a few options that will favor people who aren’t giant power monsters. DZR After Party Series is a good one to look at if the times work for you. Always a climb finish and it’s often a custom route that makes it a little more interesting.
Also VirtuSlo runs some races using zwiftracingapp ranking categories (which is seeded by compound score not just w/kg), so those would be interesting to look out for too - depending on where your category falls etc…
Totally get where you’re coming from: w/kg categories in general are not ideal particularly when the race is mostly flat.
I’ll be very happy if/when we switch to a results based seeding a la zwiftracing dot app
As far as Zwift physics go, my impression is that aero drag is based on height and rolling resistance on weight. But IRL, someone of my exact height who outweighs me by 30kg is going to be a lot wider and thus will experience more drag.
Of course Zwift also assumes we’re all positioned on the bike the same, too. And bar tops v hoods v drops makes a huge difference IRL.
So IRL, I can go downhill pretty fast with good position even as a relative lightweight – Not as light as Juan, sadly! In Zwift the 100kg guys are very hard to even draft on the big downhills.
That’s my 2c
Yet, I select a random well attended event in Zwiftpower, such as event ID 389626
Scroll thru the results first filtered on A, then B, then C. Look at the times and look at the weight column. Seems pretty rational in that with a quick scan, I don’t see any obvious skew that all of the lightweight riders are all finishing last in each cat.
Is the answer not, the watts floors are in place to support light riders? Hence you can go over 3.2wkg but as long as zFTP is below 200 watts you wont get promoted?
Personally speaking, the watts floors need reviewing - No compensation is provided to bottom of cat riders who get chewed up every race, but have a low weight and you can race in the lower category and dominate it like lots of weight riders do so they dont need to go through that same pain.
totally agree with you Juan, I’m a bit heavier at 148 but constantly put out more wkg just to keep up with the 190+ riders.
Outside i’m pretty competitive in Crits due to good position and drafting and an okay sprint.
I’d look at Zwiftracing.app based events and as @SeattleSauve said the vrituslo split cats events are really good as they use compound score as part of the criteria so the watts monsters get moved up or stay the same but lightweights get potentially moved down. For me as a mid B i get the race C in those events and can be in the front of the race even on flat courses.
Hopefully Zwift Racing Score will be better when it comes back and results based cats will be a great improvement over the current CE
I think that’s the intent of the Watt floors, but the result of having an arbitrary limit is… arbitrary. People one Watt below the floor can do infinite W/kg and never get upgraded. People one Watt above the floor have the experience Juan is talking about. These are both bad outcomes.
Hi John, I couldn’t find that event… maybe a digit is missing? Also, be sure you’re looking at race results and not fixed time events, such as ones that are exactly 1 hour long. In those, I’ve finished 20 spots and 10 minutes behind leaders, only to see me posted at the very top of the results. So look for races having different finish times across the rides, as opposed to everyone having the same finish time.
Also, take a look at the C results of race event 3932951. This was one of my teammate’s WTRL/Zwift races this week. Ignore the first rider, he dominated the event and should probably be a B rider. However, examine the next 20 riders and you’ll find several weighing near 60 kg and putting out 3.5 w/kg, and finishing 10-15 spots below heavier riders putting out 3.5 or less w/kg and finishing much higher. Granted this isn’t an exact science since we don’t know how much these riders drafted, etc. in the race but it shows the discrepancy. Small rides regularly feel this difference. If I were a large rider, I would never care or notice it since it’s not hurting me. Here’s the URL to those results:
If you’d like to see this in action, just let me know and I’d be happy to demonstrate this while riding alongside you on Zwift during a private meetup to show you the difference. Just let me know and thanks for your thoughts.
This is true. I am 55kg and I have to output 5% more W/KG on climbs and 20% more on flats to stay with the group. Sometime 30-40% on the flats. Every powerup is geared to heavy riders and I struggle to hold a C pace and Zwift Power puts me in the B category because I can generally hold 3.5 w/kg on the Alpe (more on a really good day). And I hav to put out the same power on a descent as a climb if I have any hope of sticking with a group. Sometimes I have to use a coffee break to stick with the group but those fail to maintain the draft half the time. While my weight gives me true benefits IRL it only puts me at a disadvantage in Zwift.
Not always though; this is an interesting topic; and Paul is bang on correct on where the issue is.
I’m fairly light, so I know the struggles we deal with, but I also won’t say we have that significant of an advantage anywhere either, mostly… we don’t, but I think everyone has made that discussion thick enough as it is.
But an interesting thing I’d like to mention, is the current leader of the Zwift Hill Club series in Cat B, is putting down faster times up KOMs than a vast majority of the Cat A riders, let alone even some A+ riders.
Where is the issue? The issue is she is being saved by the 250w ceiling into Cat A Open.
Some now may go and look up who is leading, and yes you will likely see my name as well, but I want to be clear that the difference here is I’m not beating top A riders on these climbs, not to mention, I’m incredibly close to being pushed up to A, while the leader is still miles away from being upgraded due to the wattage ceiling.
It’s tough to fully develop an argument for routes that are flat or rolling, or even hilly…
But when you look at climbing segments, which we can with the Hill Club series because it’s literally based purely on KOM times, and you’ve got someone able to put down times faster than a lot of the As who have signed up, but might never see an upgrade; meanwhile, people below her are getting upgraded, and putting down slower times?
This is absolutely issue that is only likely to become more apparent and likely taken advantage of.
I asked my friend ChatGPT about this and this is what he said:
"The weight-based categorizing systems, or watts per kilogram (w/kg), considerably undermine heavier riders. This system pegs a rider’s performance on their power-to-weight ratio, often resulting in unjust categorizations when it comes to races - and this is something that lighter riders equally face a challenge with too.
For heavier riders, the primary challenge lies in climbing hills, where the gravitational pull can make it harder to maintain speed and momentum. While on the surface it may appear that lighter cyclists would have an advantage on uphill rides, the truth is, that they face just as many challenges. The primary reason is that the w/kg system doesn’t consider other vital factors in determining a rider’s performance such as aerodynamics - which heavily favors heavier riders on downhill and flat terrains. It also does not consider overall fitness as heavier cyclists may have a larger power output than their lighter counterparts.
Furthermore, categorizing by the w/kg system may result in “upgrading” light riders into categories with heavier riders who overall generate more power. As a result, lighter riders end up facing an unfair disadvantage in races with a lot of flats or downhill sections where absolute power (as opposed to power-to-weight ratio) dictates speed.
Ultimately, both heavier and lighter cyclists face their own unique set of challenges under the existing categorization system. As such, it’s critical for organizers to consider better, more equitable categorization methods that not only reflect cyclists’ physical attributes but also their skill sets and capabilities. This will ensure a more inclusive and competitive environment for cyclists of all sizes and abilities."
I couldn’t agree more. If we got categorized by how well we performed in different race types. I wouldn’t care if I was B on flat C on rolling and D on hilly, as long as got matched with riders of the same abilities so I could experience tight and exciting racing.
Some will argue that it is not exciting to have tight racing, but the contrary is that making heavier riders shine on flat races and lighter riders shine on hillier courses, is just trying to boost the ego of one type of rider. If you are better than your peers, that is worth more IMO. Being better than the kids in the children’s garden doesn’t give me anything.
The problem is that most races on Zwift are flattish, and therefore favor heavier riders. That can’t affect the categorization system. What if a lighter rider is only riding hiller races?