Is it just me or is Zwift now even more favourable to lighter riders on the flat? Has there been some sort of adjustment?
I’m 78kg and when I’m putting out average of 350+ on flat courses I’m finding it hard to keep up with riders who upon closer inspection are 50-60kg.
If they are doing the same w/kg as me on the flat, for example 4.5 - I am doing 350 watts, they are doing 250w.
On the flat w/kg does not matter, absolute power is the key.
55kg riders would not be winning flat elite races with 275w averages in the real world, how is this so possible online?
Has this been tinkered with to make the flats easier for light riders? I have seen this claimed in places, and that lighter riders had complained to Zwift about their disadvantage on the flats.
If so, this is a complete distortion of the physics of cycling and is making racing unrealistic and unfair.
Imagine if Zwift pandered to heavier riders by making climbing all about absolute watts, not watts relative to bodyweight.
On the flat w/kg does not matter, absolute power is the key .
It is not that linear. In the flat what matters is watts/CdA. So smaller/lighter riders might have a smaller CdA (i.e. small aerodynamic footprint). One simple real life example would be Remco Evenepoel vs. Fillipo Ganna. Remco is the current time trial world champion mostly thanks to his smaller aerodynamic penalty coupled with good power.
How does this work in a Zwift peloton, though? I keep finding myself averaging 330-340 for 20 minutes in a flat race, and then I can’t stay in the bunch. But much lighter riders - who are also only riding in the bunch - are staying up front with averages of 260. If we are both drafting as much as possiblem what effect does CdA have? How can we both hold the same speed drafting on a flat road, with a difference of almost 100 watts?
I used to be a 70kg lightweight rider (by Dutch standards).
If a few 86kg well nourished Dutchmen with an FTPs of 400 strung the bunch out in a long line on the flat, with short full gas efforts of 500+, us featherweights would do exceptionally well not to get dropped.
In Zwift your CdA is calculated based on your weight and your height. The heavier and taller you are the greater the CdA ‘penalty’.
As for your claim of averaging 330-340w in a flat race, that seems really high even for top elite races for you not to be able to follow the main group.
So maybe you are not drafting efficiently (i.e. doing the minimum possible effort without losing contact) (?)
Maybe you are wasting too much energy in sections where you don’t have to and then get dropped in crucial moments (?)
Just speculating, it’s difficult to say without analysing a given example.
Both matter, but Height seems to be more impactful than weight. It is easier to draft or maintain a speed for a given weight/wattage. When you get a small and light rider up the road it can be a real shock.
As one of those very light riders, I can assure you nothing has changed. Everyone with lower w/kg and more watts is usually faster on the flat than me. Heck I have to do 5w/kg when overtaking to avoid getting parked behind some bigger rider going easily, then they can easily draft me with far less w/kg and stay there. I have to do huge effort to get rid of them out of draft.
Or usually I just do a u-turn when I want to be left alone.
I’m also relatively tall for my weight so I have that against me.
According to zwifterbikes, for Tempus Fugit on a TT bike, those take about the same time (27:05):
190 cm, 90 kg, 360 W (4.00 W/kg)
160 cm, 55 kg, 256 W (4.65 W/kg)
That’s 0.65 W/kg more for the lighter rider, but also more that 100 watts less, which IMO is questionable for the flattest route in Zwift. (That is encouraging weight doping even more, I am afraid.)
Note: According to zwiftinsider, drafting does not change depending on rider size.
i think zhq staff member davidp from upthread actually linked the model it was based on at one point. i forgot it, though. it could be that one. emphasis on “based on” also. i mostly remember that because it was like the one time a staff member posted something insightful about how zwift dynamics actually work and people didnt have anything negative to say about it
I think it’s overly simplistic to claim that frontal area is directly proportional to height across all heights. This might hold true for the riders Bassett et al. studied, who were 1-hour record holders, but I doubt the study included shorter, lighter riders or taller, heavier ones.
The frontal area would only scale linearly with height if the riders were sitting fully upright, exposing themselves to the maximum amount of wind.
@DavidP You can likely confirm or refute my analyses.
I asked GPT to make this work for stated extremes and it gave me 3 options. All make some sense, it also disagrees on the actual Bassett formula from above…
But essentially; adjustment factor for height or weight distribution or both I.e.
• c_H is a correction factor for height, which could be empirically derived.
• H_{avg} is the average height for typical cyclists (around 1.75 meters).
• When H is much greater than H_{avg}, this term will decrease the growth of the frontal area.
so my theory about this, based on absolutely nothing concrete as usual, is that the extremes seem more extreme because the cda for everyone is low across the board… faster speeds amplify small differences that would be less consequential at lower speeds, decrease margin for error when it comes to things like timing a sprint or taking last wheel in a TTT, cause issues with getting spat on a descent at 100kph, etc…
i’ve done a couple road bike TTTs on zwift recently (like in the old days) and it’s remarkably easy compared to doing them on a team of TT bikes. since the speed is lower
Don’t know about making ie easier for lightweight riders on flat, didn’t feel that one bit as a light rider myself.
But what I feel every race is my regular 3,8w/kg output on declines just to keep up with heavier riders who can stop pedalling at all and still be faster
Yes, we can hide in draft and keep up with lower watts, but it’s not all sunshine and rainbows
