Afternoon
I’ve been using TR now for around a year - my setup has always been a single power meter (Wahoo Kickr Core) - this has always been my single version of the truth.
I’v recently, in last month, purchased the Assioma UNO pedal so I can start training to power outdoors as well as in. As a 'sense check ’ I wanted to see how close the two power meters were, so after some googling I transferred the pedals to my bike sat on the kickr - I’ve then done the following;
- Connected the UNO pedal to my Wahoo Element Bolt
- Connected the TR App (on iphone) to the Kickr Core
I calibrated both the Kickr and UNO pedals - the pedals I used the Favero app first, but the also the Wahoo Element head unit and I’ve calibrated the kickr with the Wahoo app and also the TR app.
I made sure both the TR app and Bolt showed 3sec power and also double checked ERG mode smoothing was off in the wahoo app. I selected an endurance workout and started the ride - it took me a few mins to realise the bolt had connect to the kickr and was reporting those numbers, so I quickly removed that from the bolt and it reverted back to the connected UNO.
I noticed the UNO numbers were jumping around (a lot - often jumping up 20/30 watts then back down) - the kickr seemed far more stable on the TR app.
I downloaded both the .fit files after and uploaded them to the DCR analyser tool - you can see where the kickr was connected to both as they are almost inline for the first couple of mins, but once the UNO’s started to record on the bolt you can see the huge deviation away from the kickr - it just seems so far off…does this look ‘right’ and can anyone offer up an explanation as they seem so far apart - I expected to see some variance, but this seems totally wrong to me?
This is the full ride;
First 10 mins after the UNO started to record;
5 min section towards the end where things started to improve;
Any advise would be much appreciated.
Ideally I want to start using the UNO to record all my indoor sessions but want to be confident (to a degree) there isn’t any issue with them.
Not sure what’s with the first 10 minutes as power seems a bit off but I would trust the pedals 8 days a week over the Kickr. Wahoo trainers are also known for their unrealistic power smoothing and creating these kind of questions anytime someone sees what real power looks like. I gotta say I kind of despise wahoo’s approach to setting false expectations for their users and they know their power smoothing is total crap, it’s the equivalent of Kim Kardashian photoshopping
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The ERG mode power smoothing is a non-issue here. He specifically mentioned turning it off for this test.
As to trusting one over the other, the Kickrs have a solid track record in general. And considering that it is true, total power… I have a tendency to place it a tad higher than any single-sided power meter. That’s just a general thought, but too often people just call the power meter better while ignoring the potential flaws in the single-sided approach.
Thanks - I’d read this too, and there does seem to be an awful lot of smoothing going on - I did ensure that option was switched off in the Wahoo App before connecting the Kickr to TR but it still seems very evident in these graphs.
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Thanks - I was mindful of the single sided PM just doing a double up on power numbers to arrive at the total. What I don’t know is whether I ride with a L/R imbalance, so that’s certainly a part of this equation I can’t quantify. The odd thing was how things improved as the ride went on - I did wonder of that had anything to do with this being the first ride on the trainer with the pedals installed i.e. do they need a few rides / efforts to ‘bed in’? Think I recall reading that somewhere - things were certainly far more aligned towards the end.
If I can get some confidence in the UNO I’d like to use them for TR using the power match feature…just worried it’s going to ‘feel’ really odd if the trainer has to keep adjusting it’s resistance and the ride / workout is not going to feel as smooth - does that make sense?
Cheers.
I would say that after 26 mins the graphs are as close as you could expect.
I’m really not sure what was going on before that point - strange that they seem to start tracking each other well at the end of an interval.
Are you certain that your shoe wasn’t interfering with the favero pod or something?
My only gripe with trainers is they measure power via some optical sensor (maybe with very few exceptions) whereas the pedals use a strain gauge. The sensor is generally fine but none of my trainers have ever consistently tracked with the DUO or even my old Stages L, the trainer would initially read high, then match the other PM, then read high or low again at the end of the workout. This is within the span of an hour id imagine a longer workout would have even more drift
Think I’d be happy with the alignment had the workout been as aligned as it was from that 30 min mark - I’m 99% sure my shoes are well away from the pod, but that’s something I can check on the next ride to be sure.
Also, was this the very first ride after swapping over the pedals? There could be a bit a settling in involved?
Yes it was the first ride after moving them over - I mentioned that in an earlier reply - it’ll be interesting to see if I get a closer alignment for the full ride on my next workout which would suggest the improvement on this first ride after the 30min mark is linked to that ‘bedding in’ process, maybe?
On the issue where you’re concerned about the workout feeling odd due to resistance changes… Why spend time worrying about it (in your head), and not just try it out? It’s not going to cost anything but a few minutes of time, its not going to break anything or cause additional wear/tear etc. Too much effort spent worrying instead of just doing.
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Not quite… but I agree that the various methods of power calc used by trainers can lead to some interesting quirks/behavior. Latest top model Peloton+ bike uses strain gauges at the resistance magnet assembly, NEO 2T and Kickr/Kickr Core use electrical math, older Kickrs used an actual strain gauge, certain Elite trainers and the top end ICG spin bikes use electro-optical measurement of the twist of a shaft (like the OLD Ergomo meters) etc. Many ways to skin a cat.
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That’s certainly another way of looking at it, and don’t disagree.
- Yes, it is best to install, zero offset and then do a ride. Include a couple of hard spring errors and re-zero offset.
Also, you calibrated the trainer, but its important to do that after about 10 minutes of rising. That gets the system up to operating temps and should give you the best results overall.
If you calibrate the trainer cold, it could see the results, and might explain some of the convergence you saw.
Elite uses their Optical Torque Sensor. They have a patent (or exclusive rights to some other companies license) on it and are the only trainer company that offers it. It also happens to be an extremely reliable and accurate system, so hinting the an “optical sensor” trainer is somehow lacking or not as trustworthy as a strain gauge power meter is a mistake, especially in this case.
For most other trainers, they are actually measuring the electrical system power and current to estimate power (based on specific formulas and actual comparison to power meters). There may be an optical sensor in use there too, but it only serves to count the rpms of the system for the power calculation. So it is also plenty reliable and quite comparable to strain gauge PMs.
I say that with the basic consideration of using the top tier trainers (Kickr, H3. Neo) because those have been shown to give reliable results in so many instances. I ignore the mid to low level trainers using similar techniques, because they don’t have the same level of care and precision.
Essentially, good trainers can be trusted as a broad consideration, while also recognizing that there are some cases where their data may skew off (high flywheel speeds in particular).
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I did the install then the zero offset on the Favero - its named ‘manual calibration’ on their app
I did the trainer calibration cold, so I’ll remember that for next time and be sure to warm it up first.
I’ll also do a few harder efforts when doing that warming up too to help the pedals - since I put them on earlier today I’ve only done the session included in the graphs above and that was just an easy endurance effort.
Cheers again for the feedback. Much appreciated.
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@mcneese.chad - I took your advice and did a 10 min warm up of the trainer on Zwift with a few efforts for the pedals - I then did a calibration using the TR app on both the Kickr Core and the UNO. I’ve then done a quick 30 min on Zwift (no ERG mode) and while things seemed to have tracked OK there looks to be a consistent difference with the UNO’s being c10-15w lower than the Kickr - I’m guessing some of this can be accounted for with it being single sided and if I’m right leg bias that could account for the difference?
Here are some quick comparisons - lower lines is the UNO ;
Do you think this amount of deviation is ‘normal’ or maybe, better put, acceptable?
Cheers.
Could be 2 things
-
a left/right difference
-
electronic brake adjustment needed on the core.
A friend of mine has the assioma duo and they are basically BANG on, just SLIGHTLY delayed on the assiomas.
If you perform an “advanced spindown” in the wahoo app for your kickr core, it will test and adjust the electronic brake as well, which MAY clear some of the discrepancy ( it dropped a friend’s “ftp” like 30 watts to be much more realistic lol )
Thanks - I read about the advanced spin down which suggested it should only be done IF requested by Wahoo - not sure what could realistically go wrong mind!
Tbh I can cope with my FTP dropping - the number doesn’t bother me - what I want to be sure of though is it’s set correctly to ensure my workouts are consistent both inside and out and, more importantly, TSS is being calculated correctly in Training Peaks.
I have a feeling I’ve a left / right imbalance - just not sure I want to spend another £400 for the DUO upgrade kit when I’ve just purchased the UNO to prove it!
Think I’ll just do another ramp test on TR using the UNO and then use PowerMatch for all my future workouts indoors.
Cheers.
