kickr accuracy

Apr 13, 19 12:48

Post #1 of 25 (2807 views)

I have riddden over 4,000 hours with a PM. I really know my power. Last couple rides on the kickr seemed like low power for my rpe and HR. Figured it could be pollen, I ride it in a breezway attached to the house and the sh!t is thick now. Today I know it was low even after a few spin downs cuz I rode with another power meter(P1's). Calibrated everything and just cruising at 135hr they were about 15% different, 33 watts apart.

Any suggestions? Like I said, I think this kickr has worked very well before now and I spun it down after 15 minutes and again after 90 minute and once more after 2.5 hours. It stayed consistent. The only weird thing is it it said the temp was 145degrees on one of those spin downs, but the power was consistent afterwards.

Last piece of info, I was predominatly in erg mode becasue I was trying to match power and hitting lap a lot. I will try again not in erg mode.

Re: kickr accuracy [DBF] [ In reply to ]

Apr 13, 19 12:59

Post #2 of 25 (2795 views)

Welcome to hell. Power meter 'alignment'. In short, yes, they should agree within a few %. The reality is often they won't.... but they should. It's a long frustrating road to get enough data to really know what is 'correct'.

Here's the process I use to compare power meters (data collection, test protocols, tools for comparison, etc): https://www.youtube.com/watch?v=JhheDLXRM7I

To answer your query on the Kickr... maybe the belt needs replacing? Wahoo Support should be able to advise.

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Re: kickr accuracy [DBF] [ In reply to ]

Apr 13, 19 13:11

Post #3 of 25 (2787 views)

My Kickr Snap was great for a year or two and then ever since some firmware upgrade it totally sucks and power is off by as much as 20%. Customer service blamed it on user error, then later admitted I did everything correctly (calibration etc) and proposed nothing to address the problem.

Re: kickr accuracy [DBF] [ In reply to ]

Apr 14, 19 10:38

Post #4 of 25 (2642 views)

May I ask which PM you are using?

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Re: kickr accuracy [grs6] [ In reply to ]

Apr 14, 19 15:08

Post #5 of 25 (2559 views)

P1’s. Calibrated and crank length all correct. And a buddy came over with a quark.

Re: kickr accuracy [DBF] [ In reply to ]

Apr 14, 19 16:06

Post #6 of 25 (2540 views)

My kickr disagrees with my vector 3's by 20+ %.

Re: kickr accuracy [DJRed] [ In reply to ]

Apr 14, 19 16:42

Post #7 of 25 (2517 views)

you got the right crank length in there?

Re: kickr accuracy [DBF] [ In reply to ]

Apr 14, 19 17:23

Post #8 of 25 (2505 views)

Interesting. We heard the same with our PM measuring different from kickr by about 35W as well. I'd trust the PM

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Re: kickr accuracy [gplama] [ In reply to ]

Apr 14, 19 17:28

Post #9 of 25 (2502 views)

You inspired me to test it some more. Gonna borrow a bike with a stages, put my P1’s on there and see.

Re: kickr accuracy [DBF] [ In reply to ]

Apr 14, 19 18:21

Post #10 of 25 (2477 views)

DBF wrote:

you got the right crank length in there?

Yes. Thanks for the suggestion, though.

Re: kickr accuracy [DJRed] [ In reply to ]

Apr 15, 19 0:15

Post #11 of 25 (2412 views)

Wait, are we comparing the "accuracy" of a Kickr to the "accuracy" of pedal-based PMs?

We need a Slowtwitch joke in which that is the punchline! I'd roll a dice as to which I believed, primarily the one that gives me the higher numbers! ;)

Re: kickr accuracy [Darren325] [ In reply to ]

Apr 15, 19 3:45

Post #12 of 25 (2352 views)

My kickr was within 2-3% for a year. Suddenly it consistently is not.
Accuracy is consistency, precision is a different matter and I think what you refer to.

Re: kickr accuracy [Darren325] [ In reply to ]

Apr 15, 19 4:58

Post #13 of 25 (2335 views)

Darren325 wrote:

Wait, are we comparing the "accuracy" of a Kickr to the "accuracy" of pedal-based PMs?

We need a Slowtwitch joke in which that is the punchline! I'd roll a dice as to which I believed, primarily the one that gives me the higher numbers! ;)

Sounds like a modification of Segal's law.
"A man with a power meter always knows his output. A man with two power meters is never sure."

Re: kickr accuracy [DBF] [ In reply to ]

Apr 15, 19 6:48

Post #14 of 25 (2295 views)

DBF wrote:

My kickr was within 2-3% for a year. Suddenly it consistently is not.
Accuracy is consistency, precision is a different matter and I think what you refer to.

See this is very similar to my experience. I thought my trouble began with a firmware update but I have no hard evidence of that.

Re: kickr accuracy [DBF] [ In reply to ]

Apr 15, 19 7:00

Post #15 of 25 (2283 views)

DBF wrote:

I have riddden over 4,000 hours with a PM. I really know my power. Last couple rides on the kickr seemed like low power for my rpe and HR. Figured it could be pollen, I ride it in a breezway attached to the house and the sh!t is thick now. Today I know it was low even after a few spin downs cuz I rode with another power meter(P1's). Calibrated everything and just cruising at 135hr they were about 15% different, 33 watts apart.

Any suggestions? Like I said, I think this kickr has worked very well before now and I spun it down after 15 minutes and again after 90 minute and once more after 2.5 hours. It stayed consistent. The only weird thing is it it said the temp was 145degrees on one of those spin downs, but the power was consistent afterwards.

Last piece of info, I was predominatly in erg mode becasue I was trying to match power and hitting lap a lot. I will try again not in erg mode.

I have a 2018 Kickr and it is typically 5-8% low compared to three different Quarqs. Even with spindowns done 15 minutes in it makes little change. On occasion it is closer to 10%, if you are doing 1 minute repeats at 500-600w then that can make a huge difference.

Re: kickr accuracy [DBF] [ In reply to ]

Apr 15, 19 7:39

Post #16 of 25 (2270 views)

My n=1

Kickr generally 1-2% lower than my Vector 1's. I've been pretty happy with the consistency.

Re: kickr accuracy [beston] [ In reply to ]

Apr 15, 19 8:20

Post #17 of 25 (2245 views)

beston wrote:

Darren325 wrote:

Wait, are we comparing the "accuracy" of a Kickr to the "accuracy" of pedal-based PMs?

We need a Slowtwitch joke in which that is the punchline! I'd roll a dice as to which I believed, primarily the one that gives me the higher numbers! ;)

Sounds like a modification of Segal's law.
"A man with a power meter always knows his output. A man with two power meters is never sure."

I have 4 quarqs and they are all within 2% of each other. Kickrs are notoriously bad. It uses a rubber belt to drive it. No way it's not affected by stretch and heat.

Re: kickr accuracy [mcmetal] [ In reply to ]

Apr 15, 19 9:16

Post #18 of 25 (2221 views)

mcmetal wrote:

I have 4 quarqs and they are all within 2% of each other.

How are you comparing the accuracy of your Quarq's? ...I'm imaging a simultaneous comparison of two different sources of measurement to know the degree of error between them.

Re: kickr accuracy [DBF] [ In reply to ]

Apr 15, 19 9:42

Post #19 of 25 (2202 views)

Awesome, I'm really curious as to the result.

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Re: kickr accuracy [DBF] [ In reply to ]

Apr 15, 19 10:20

Post #20 of 25 (2183 views)

I gave up on ever trying to get my indoor trainer and outdoor power to be perfectly aligned. I honestly got to the point where I had an indoor FTP and an outdoor FTP.

The important thing to me really was that they were both consistent, they just were apart by about 10%.

It works for me because most of my winter training is done inside. Once the weather clears up and I head out, I just do an outdoor FTP and set it. Though I can almost just add 10% to my indoor FTP.

Re: kickr accuracy [beston] [ In reply to ]

Apr 15, 19 11:10

Post #21 of 25 (2160 views)

beston wrote:

mcmetal wrote:

I have 4 quarqs and they are all within 2% of each other.

How are you comparing the accuracy of your Quarq's? ...I'm imaging a simultaneous comparison of two different sources of measurement to know the degree of error between them.

From different tests over time. Mainly I've tested them on my Velotron to establish baselines and have done numerous FTP tests and rides on each as well. I also use a known weight and check/set the slope periodically.

Re: kickr accuracy [mcmetal] [ In reply to ]

Apr 15, 19 12:57

Post #22 of 25 (2120 views)

i was under the impression that there will always be a small difference between a crank/ pedal based PM and a rear wheel based one due to loss over the drivetrain. I suppose this difference gets larger the worse your drivetrain is, however I can’t see this causing the problem here.

I have a Kickr Core and it typically reads 10% higher than my 2 Stages PMs. However I get over this by getting the trainer to derive its power from the PM (an option you have on the app). Therefore I get ‘outdoor’ power ‘indoor’.... I’ve tested this by measuring different powers on different head units and it’s seems valid... ie there is very small difference between the two with the crank based measuring slightly higher which makes sense in my eyes at least...

Re: kickr accuracy [Stimps9] [ In reply to ]

Apr 15, 19 13:08

Post #23 of 25 (2111 views)

Stimps9 wrote:

. However I get over this by getting the trainer to derive its power from the PM (an option you have on the app).

I do this, as well (power match on Trainer Road). Uses your PM to offset the resistance of the Kickr and removes the Kickr's PM from the equation.

Your favorite mafia sucks.

Re: kickr accuracy [DBF] [ In reply to ]

Apr 15, 19 13:54

Post #24 of 25 (2093 views)

Also, I've heard about this :
https://www.smartbiketrainers.com/...ou-should-do-it-5726
I've suggested it to a few customers, but I don't know of anyone that has gotten it to work.

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Social : @tempopowermeter

Re: kickr accuracy [grs6] [ In reply to ]

Apr 16, 19 5:49

Post #25 of 25 (2017 views)

grs6 wrote:

Also, I've heard about this :
https://www.smartbiketrainers.com/...ou-should-do-it-5726
I've suggested it to a few customers, but I don't know of anyone that has gotten it to work.

On Zwift this works completely seamlessly and I don't see what element of it would cause it to fail on any other programs. It is more difficult to verify its not working than to get it running in the first place.

You can always double check its working by connecting the trainer power meter to a different headunit/program while running your main program off your power meter. For example my Tacx utility app will read power from my smart trainer while Zwift is reading power from my PM. The numbers are always slightly different indication the whole system is working.

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