Tacx Support: 12% loss in power via drivetrain is realistic

My weight is always 70kg, even if I currently weigh 4 or 5lbs more lol

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For the Zwift invitational races we need to provide a video weigh in according to a specific protocol, in cycling kit and socks (no shoes) within the preceeding 24hrs of a race.

There was also a fairly lengthy test protocol we had to send to ZADA of us streaming a specific test course (efforts closely aligned to a 4DP test), dual recorded on powermeter and smart trainer. As part of the test we had to film and show the calibration values. Zwift know a lot about the equipment that we use including make, model, serial number firmware version etc.

It is improving, but there’s a long way to go.

I suspect the next step will be a Zwift proprietary trainer with the ability to be hardwired to the PC and calibrated remotely at Zwift’s end.

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Something like that is bound to happen when the racing gets more serious and more money is on the line. This is basically how it has been done for a long time with indoor rowing world championships etc. They have been using power for a long time, and settled on a standardized equipment.

Better than nothing, but you can cheat all of those steps. I won’t list them, but I can think of ways to bypass each one of those.

The sad part is that cheaters are going to cheat.

And for the Zwift trainer thing…established companies have problems hitting their accuracy claims (although some are better than others). I doubt we’re going to get a perfectly accurate and precise trainer from Zwift the first time out of the gates.

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Just build in some sort of scale within the trainer that takes weight measurements every second while you ride, that way I doubt someone could cheat it mid race. There has to be a way to make this work :sweat_smile:

  • I can already see ways to mess with it.

I think Zwift wants to go after peloton. The last thing peloton riders want is to get weighed every time they get in a bike :smile:.

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Or see their real power numbers.

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they could make it so you cant see that data but its sent to zwift in the background and cross-referenced to what you inputted, but ahah agree with you there 100% also zwift isn’t paying me so ill stop wasting mental energy on their issues :slight_smile:

That’s very true.

I think gym exercise equipment (like an elliptical) over estimates your calorie burn on purpose.

Lots of non-cylcists probably do 100 watts in an hour and burn 200ish calories. Some people do a lot less.

It’s not uncommon for a smaller women to have an FTP of 80 starting out, so in a hard ride they might do 60 watts average.

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I’m getting images of those circus performers that suspend themselves from hooks! :rofl:

@AndyGajda Thanks for the rundown on the requirements. I get why you’re peeved now.
To be fair to Taxc, you’ve got an old Neo and a new 2T that are obviously years apart in age and still read within 3%. That’s seriously impressive!

One thing that does strike me as odd about the whole trainer accuracy debate is that there seems to be no mention of time in the accuracy claims. Short of testing every racers trainer on the same standard testing rig immediately before a race and afterwards, I dont see how they’re ever going to make esports fair.

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For example, if you put your scale on soft carpet you’ll read lower than if you’re on a concrete floor.

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I have two sets of Assioma Dual power meter and measure about a 3-4% difference at the pedals vs Tacx Neo 2T.

Speaking of throwing off scales with an inconsistent floor, Have you lot played around with suspension on trainers? It’s on my long list of things to test out.
(I’m doing Clark atm. Those bursts really catch you out if you’re not paying attention).

This article is worth reading.

This is the table summarizing the results. PMs from all brands have a non-zero deviation, and a range around that deviation - meaning variability in accuracy of different PMs of a given make/model.

image

And a scatter plot of the data:

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And a relevant quote:

“ Mean deviation also gives us a fresh perspective on the marketing claims of power meter brands. Let’s use SRM as an example (and that is only one example from a whole range of brands) and a claimed accuracy of ±1%. Most customers may think this means each and every power meter is ±1% accurate, but it is more likely this relates to the overall average.”

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We had a team managers Zoom call with ZADA and without going into specifics, I was more reassured that they are trying to get around most of the ways I suspect you are thinking about to bypass those systems :slightly_smiling_face:

Nothings perfect, and it’s a new discipline. If you look back at the history of the Tour De France, the lengths people would go to in order to even finish a stage was incredible! The amount of stimulants you needed to take was almost a badge of honour!!! That’s really where we are with eRacing.

(Although not a current TR subscriber, I was using it from 2013. Definitely changed the way I view training, and certainly wouldn’t as strong today if it weren’t for Sleeping Beauty, Silvertip and the disgusting 20 min test!!! Thank you :star_struck:)

For esports, it’s not just about eliminating cheating. It’s also about ensuring sufficient accuracy, even if someone is not looking to cheat. That’s a tall order.

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Wow, talk about a worthless claim if that is what they mean. They could have +/- 50% between individual meters, and still have the right ‘average’. Lies, damn lies, and power meter/smart trainer accuracy claims :slight_smile:

Do you mean riding a MTB on a trainer? Yes, I’ve done that a bunch and I like it. My epic is sorta locked out where I get a bit of play but it’s still firm. Helps with the bottom.

I’ve tried a rocker plate too but I found that gave me saddle sores. It made me slide fore/aft on my saddle a lot.

I meant testing to see if it throws off the power output between the pedals and the trainer? I’ve often wondered if it makes much of a difference. ( similar to a set of scales on soft flooring).
I do much the same thing as you on the Spark and run it in the half locked out mode so the seat sits up a little bit more than full sus mode. It seems like a good compromise between full sag and locked out.

I’ve just received an email confirming my rego for the 2021 Croc Trophy. :partying_face: :cold_sweat: It’ll be nothing but MTB on the trainer for my foreseeable future.

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