Zwift Racing Problem 28kg Rider

Hello all,
I have recently run into a problem in Zwift while doing a race. I am 28kg and I’m u15, but I have to push over 1w/kg more then most adults to keep up on the flats, 0.5w/kg more on the hills (but my weight should be giving me an advantage on the hills) and around 3w/kg more on the decents which is absolutely ridiculous! In real life I can keep up with my dad on the decents easy while both of us are freewheeling. Can someone tell me why this is happening and contact Zwift and ask for them to fix this problem (like I have already done) if you are having this to,
Ride on!

This is not a problem. It is just how cycling works. You are 28 kg so you can do a lot of wpk. It is not just wpk that matter. It is watts that will impact your speed too. A 28 kg rider will not be going the same speed as 70kg riders down a hill, or on flats.

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…and what make you think that on descents your father isn’t feathering his brakes. As a heavier rider, freewheeling downhill is one place I can easily beat others both in real life and Zwift.

28kg is extremely light … when you say under under 15 , how far , that is a 0 percentile stat of a 14 year old. Either way your weight puts you into the extremities of what zwift can probably cope with .

There is plenty evidence that Zwift unfortunately does not accuractly represent performance for such weight percentiles , normally over reporting it but at this point perhaps it could go the opposite way , either way its not uncommon for virtual performance to be unreliable.

To highlight what you are aluding to , At this weight 0.5 w/kg is only an extra 14W and 1/w/kg 28W. But for those you are comparing too are like pushing 70W-100W more than you at same w/kg

So what you are saying is a problem actually may be more a problem for others as despite your weight advantage every other parameter is blowing you out of the water and why you are (or should be ) being dropped.

I would suggest just like in real life you should seek out Age group racing ( if it exists ). Most racing affiliations that I am aware of would not support you racing in adult races . For many reasons , but I think the same should be the case in Zwift too . Not least because you will not experience the issues you have highlighted . You will certainly find a more equitable and enjoyable competition however and one appropriate for your physiology.


All good points but I’m still not sure why it’s not giving me an advantage on even the steepest of gradients? I’m still having to push harder on climbs! Oh, and I’m am also 11years old and 140cm.

Look at the actual physics (I use An interactive model-based calculator of cycling power vs. speed)

I’m 90kg and 180cm. So you’re a 1/3rd of my weight (big advantage) but only 7/10th of my height (still an advantage but not such a huge advantage once we’re both down on the drops).

To cruise along at 30km/h on the flat you need to put out 96W which is 3.4W/kg. I have to put out a lot more power, 156W, which, because of my mass is only 1.7W/kg. So the W/kg might misleadingly make you think I’m doing half the work rate even though I’m having to produce more power.

If we switch to a good 10km/h on a 10% climb, you only need to put out 98W whilst I have to find 286W. That’s not surprising - I have to put out almost 3 times the power because I’m 3 times your weight. But in W/kg terms you’re doing 3.5W/kg whilst I’m doing 3.17W/kg.

So hopefully, you can see now how Watts per kilogramme isn’t very useful when comparing riders at totally different ends of the weight spectrum. Stop looking at it unless you know the other rider is also sub-40kg like yourself.

Meanwhile Zwift aren’t cheating you. Their model is working on power, height and weight to calculate your speed. If you can beat that 98 Watts you will be at the top of Alpe du Zwift before me because 286W is me on a very good day (240W was me today).