zPower: Don't be a "Flier"

(Chris B (D)) #321

Oh, all along I thought the request was to separate z-power riders from power meter riders, as some z-power riders have their set ups wrong and the power riders can’t keep up. But if the plan is to just allow categories, such as:

  1. Training, no leader board

  2. CAT 4

  3. CAT 3

  4. Etc

That would be just like Strava premium letting me see my age group on leader boards. That would allow me, on a z-power set up that produces speeds/rankings 10% lower than I see in the real world, a chance to compete against similar strength riders, regardless of if they’re on z-power or power meters. The current flier flagging will still work to notify all fliers, be they power or z-power 

this whole separate leader boards for an arbitrary item of trainer type, rather than cheating vs not cheating, seems to be quite a red hearing. 

(Marcus Durant @VanelliCycling) #322

I just installed Zwift on my workstation, Damn the graphics were nice! (NVIDIA Quadro K4000)

I was expecting to find some kind of shenanigans withing the 10 minutes that I watched and paste the image here under Steven’s post but was pleasantly disappointed. Everything looked plausible. Riders were sprinting for the sprint, putting out decent numbers, plausible times on the climb etc and then crucially having to ease up afterwards after big efforts.

As I said before, I’ve not looked at the game for a little while now, probably a month or so so maybe things have improved (though people keep adding to this thread so it cant all be a good experience)

I also don’t think limiting people on zpower trainers is a very fair solution, some people are actually monsters! 

(Dave Turpin *USMES* Rogue Velo) #323

Well, it seems like a lot of the arguments are cooling down. 

But what I meant before when I said I would not buy a power meter. I won’t because I don’t need to. I will spend the $500 on a new set of wheels before I buy power, because the belief that strain gage power meters are accurate and other methods are not is flawed. 

Yes, there is a learning curve. But the estimated power I get on Strava and the power I get on Zwift are very close, and the power I produce when I get KOMs in Strava, place in actual races, and so forth is good enough. The funny thing is that in order to properly calibrate a strain gage, you need to use a dynamometer.  A dyno is really just a fluid trainer. A commercial-quality one, sure, but the same idea. Therefore there is no reason that a trainer with a proper power curve would not be as accurate, or more accurate, than a strain gage glued to a beam.

“Smart” trainers don’t have actual power measurements in them either.  They are just a trainer with a built in power algorithm.  

in any case, the overall discussion is how to deal with cheaters?  I think by now it has been proven that anyone can cheat, regardless of how they get their power. I am a proponent of the Caution flag system currently in place. It’s seems to get flyers whether zpower, meter puffer, or weight cheaters. 

Just make it more of a penalty. Deny them jersies, and boot them straight to the ant+ page to reconfigure if it continues.  Also is there an ability to flag riders?  I’ve not seen it, but if there is, use it. Taking the time to flag messed up efforts on Strava has made that platform much more competitive. 

(Ben Crone) #324

The fact that you completely disregard the value of a power meter based on Strava’s estimated power calculations pretty much wipes out any credibility you might have.


The funny thing is that in order to properly calibrate a strain gage, you need to use a dynamometer. 


“Smart” trainers don’t have actual power measurements in them either.  They are just a trainer with a built in power algorithm.  

I don’t think anyone is really doubting the output power from smart trainers

(malcolm may (WCC) C) #325

Ben Crone - not doubting smart trainers is not smart. That’s the problem. The simplest cheat on a smart trainer is to lie about your weight. Forget about poor set up. Just drop your weight and you ride better than a pro. And seemingly under the radar. Apparently smart trainer users are all sensible, serious, superstars. Not lying sausage suckers. Which seems to be a common theme for ‘zpower people’. 

(Stewart ) #326

Mal, weight has no bearing at all on power figures on a smart trainer. Weight altering will give slightly different speeds on Zwift and can be done on a p.m., smart or dumb trainer.
If you can’t put out the power then you will not ride like a pro on a smart trainer.

I am sure the Kickr has a strain gauge but most others use algorithms and some are very accurate such as the Computrainer.

(malcolm may (WCC) C) #327

Of course weight has an impact on speed. I never mentioned power readings in my post. Power is power.

But I have had people shoot past me while they are doing 180 w and 5 wpk, so its that they weigh less than 35 kg that’s the issue. Not the power.

(Stewart ) #328

They won’t shoot past you at 180W even at 5w/kg. It is the Watts that matter.

(malcolm may (WCC) C) #329

ok. I see no point in an argument with a stranger

(Ben Crone) #330

Mal, you’re on your own.

People deliberately setting their weight low to inflate their W/kg figures is unrelated to trainer type. I have a power meter and could just as easily do that as those with smart or dumb trainers. 

What Stewart is saying holds true for the flats but not quite on the climbs where W/kg is more important.

(Michael Meysarosh) #331

Zwift had a blog entry that stated the the factors used when calculating your speed. 

Your speed in Zwift is determined by three things:

  1. Watts: the more power you’re putting into the pedals, the faster you will go
  2. Weight: lighter riders will go faster than heavier riders if both are putting out the same wattage.
  3. Game physics: inclines, draft effects, road surfaces and which bike/wheels you’re using all affect your speed.

So Zwift mirrors the real world, mostly. The most obvious detail missing in the speed equation is the lack of wind: but that’s kind of nice, isn’t it?

If Zwift is using typical models developed for a cyclists, we can assume the following;

Weight will have an impact upon a rider’s speed on a flat surface, but it will be greatly diminished as speed increases since drag effect will become the major factor. Sure, a lighter rider will be faster when putting out the same wattage, but only somewhat on a high speed flat.

We can also expect the bike/wheel choice play another significant role on these situations as its been well demonstrated with much a TT bike can save over a typical TT course. Zwift responds to this and removes certain bonuses when riding a TT bike. I might also guess that the heavier rider would likely have a small advantage on descents as the greater weight includes a greater force driving behind it.

The final reason someone would pass you at speed is the applicable use of bonuses strategically used. When those rewards come in the right combo, it can make for an interesting ally in the speed wars. 

(malcolm may (WCC) C) #332

I punch over 1100 watts on the sprints and can barely get inside the top 10% of those riding with me in the session. Climbs absolutely no doubt. Though I am averaging 400 watts on Watopia and getting just under 3 minutes - while others pushing far less are scooting up 40 - 50 % faster.

So its not so simple. What you enter as weight is one thing. But I can’t hit more than 41 mph or so on the downhills, even when I am laying down the watts. Zwift have calibrated my Lemond Revolution, but it nothing like my powertap out doors as far as result for effort. They may just be the trainer and its capabilities.

So there are a lot of calculations which are not in alignment with the outdoors. I am saying that the logic which should apply here very often doesn’t. Simple example. A 200 m sprint where there are no gps start and finish points. I average 29.5 mph for 27 seconds. I used to run faster (21) out of blocks, and while I was ‘good’ I never hit more than 25 mph. And that’s not an average. Nor does Usain Bolt, and he runs 19.18 from blocks. I have a weekend riding buddy who had the same average, the same time, and did it with half the watts. Good for him.

I think there are a lot more anomalies here than we have identified. In the big picture its likely ok, but under the cold light of day, maybe not so much.

(malcolm may (WCC) C) #333

yep. Read them all. And they make sense. But are they accurate? 

Are the calibrations used in Trainer Road for example, the same as those used in Zwift? I know we’ll not find out, but I wish I knew.

(Michael Meysarosh) #334

They may not be anomalies but are more so variables in the physical models and bonus combinations with some strategic planning to get the green.

First you have the two key bonuses, which is the aero boost and draft bonus. The amount of drag reduction on the aero boost isn’t clear, but the drag boost is a 70% reduction and if used with a good lead out, could easily explain that difference. Especially if one rides in fast group. In a group, the incoming momentum one may gain could easily provide a better sprint time as compared to the differential power outputs between two riders.

Another key explanation is the use of an improperly configured manual resistance trainer that greatly exaggerates the resulting power in Zwift.

I do think Zwift added this to create the feel of strategy being critical to wear the jersey. This often being the case in the pro level’s where the lead out and distance from where the attack begins playing major parts.

(malcolm may (WCC) C) #335

Hey, I’m not comfortable with the calibration of my trainer. Which they did and was grateful for at the time. I sure as heck am not going to credit anyone the higher functions you are talking about. Especially when the simple ones are unexplainable. Like the example I gave with the 200 m sprint section. 

(Craig Howard KISS B) #336

None of this matters! 

Most dumb trainers seem to be over outputting but who cares. Mine was skewed all over the place, my power meter aligned at 150W and then it goes way out the more power you output. 

I’m 135-137lbs. At less than 200W on a 0% grade, I’m going way over 22mph. No way in the real world would this happen unless I had a healthy tail wind, but Zwift has no wind right? 

My point is this, the island is skewed in terms of real power and Z power, ANYONE can alter their weight and cheat themselves (pointless). If you are a Z power user, just be grateful you have a nice platform upon which to train for a measly fee of about 2 dollars unless you’re in the UK like me where its £8 and also where the real roads are dangerously broken and are gridlocked and drivers hate you so much they ‘punish pass’ you. 

Its a game. Not real life.Youll all be comparing average speed next… *lol*

(Michael Meysarosh) #337

Its a computer model that has value placed upon the drag that rider would experience at a given speed. So if your not the same speeds outside, then you can safely assume the components of your drag are greater than the model Zwift uses. That could include wind, rolling resistance, and mechanical resistance increases.

So maybe if you add in the skin suit, a wind tunnel bike fitting combined with endless yoga sessions to get comfy sitting so low, all the ceramic bearings and ultra low rolling resistance tires you can get your hands on and every wind cheating component out there. Then you would finally match your Zwift flat speed.

You’d likely be broke as well, but what does that matter!


(Chris B (D)) #338

“If you are a Z power user, just be grateful you have a nice platform upon which to train …”

why should z-power users be grateful and not just all users? 

Rode again last night. One 5-6W/kg person going really well on z-power, all other fliers were power meter. Inwas doing FTP test, so the leaderboards didn’t apply to me anyway and I just had a good fun productive ride, for which I am grateful. 

(D) #339

I’m probably going to regret asking this but what is this 200m sprint?  Is it the reverse Watopia sprint?

(malcolm may (WCC) C) #340

you’ll have to find it yourself. Its not reverse, and its on Watopia. I can’t identify any of these things, except for the signposted ones.