Sigeyi Axo Power Meter Spider

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TobinHatesYou
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by TobinHatesYou

I’ve pretty much settled on Garmin. 3 sets of Rally/Vector 3. Everyone has their own priorities. Mine’s having consistent hardware across all my bikes and pedals are the easiest way to achieve that.

I did just preorder the Verve Infocrank IC2…They’ll probably be disappointing somehow.

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arcatern
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by arcatern

RyanH wrote:
Sat Oct 15, 2022 3:36 pm
gplama wrote:
RyanH wrote:
Sat Oct 15, 2022 5:01 am
robbosmans wrote:Curious, is there a perfect powermeter?
*cough* SRM *cough*
SRM left the chat a long time ago. Their SRM X-Power SPD pedals are an embarrassment.

I just wish Shimano would buy them out and improve / innovate / integrate their tech.
Sure, they came out with a bad product but I don't think I've seen you test their spider based power meters. I've had 2 dzero dub PM's recently that had up to a 5% left right discrepancy and power over read on them up to 8% high as force increased. This is based on calibrated weights and baseline hill repeats. I can't even keep the Quarq baseline consistent with static load whereas my daily driver SRM is reading within 1% of when I last tested it a year ago. I've also had two other dzero dub that output weird numbers too but I didn't check LR readings. Either way, it's something that I haven't seen you or DC Rainmaker point out.

At the end of the day, a power meter is a training tool and its sole purpose is to give reliable data. Stages, Quarq and Shimano don't meet that mark. I have tons of data to prove that. SRM may not have the latest features but it's the only PM that I don't have to worry if the numbers on the screen are off or not.

I'm a data geek like you, so I've had about 40 PMs come through my hands (over half of them SRM - I have 6, going on 7 SRMs at the moment). I calibrate all of them with a certified weight and validate their outputs on a fixed distance steep hill. My calibrated SRMs match SRMs that just come back from Colorado (within 0.5%). My other PMs are all over the place.
sounds like you've put a lot of different units through their paces.
what's your take on sigeyi axo, power2max (ng eco, if you wanna be specific), 4iii dual?

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pdlpsher1
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by pdlpsher1

I have a question to you PM experts. My friends and I all have various different PMs. When I analyze the dataset I see some differences in terms of data smoothing. I assume all of us are recording the data in 1hz interval. But certain PMs seem to take multiple power readings continuously and take an average over the span of one second and then pass that figure over to the head unit. Whereas other PMs will take an instantaneous power reading once every second. The end result is that when the power data is plotted in a graph, some PMs data looks more jagged while others look more 'smoothed'. So far this is my observation between the various brands.

Quarq- heavy smoothing going on. The data that is passed to the headunit is already smoothed.
Garmin Rally- it appears that no smoothing is applied but the data should be less jagged than Stages due to it being dual-sided.
Stages- it appears that no smoothing is applied.
P2M- it appears that some smoothing is applied. Data looks more consistent than the Stages left-side only and Rally, but more jagged than Quarq.

On the surface I would think a PM that takes multiple samples within a one second interval would provide more accurate data than on that takes a single sample every second. Does anyone know the sampling frequencies between the various PM brands? Other than making the power graphs look prettier, is there added value of having a PM with a sampling rate higher than 1hz?

Here's are some examples of what I'm talking about. All four of us rode together at the same pace on the same Strava segment. The first two graphs are Stages left-side only. Graph #3 is from a dual-sided Garmin Rally. Graph #4 is from P2M NGEco. The Quarq rider wasn't part of the group, but if he had been his power graph would look even more smoothed than the Garmin Rally. Graph #5 is the Quarq rider on the same segment but on a different day. You can clearly see the power data being heavily smoothed.

Stages
Image

Stages
Image

Rally dual-sided
Image

P2M
Image

Quarq Force DUB
Image

TobinHatesYou
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by TobinHatesYou

My Quarq output is quite jagged, as are all my other power meter readings. I have a very ugly pedaling style. It seems possible this 5th person rides with incredible souplesse. Also on rides where I go for a sprint the y-axis gets compressed to accommodate the huge range between zero watts and my max instant power. That makes power graphs look smoother when zoomed in. However that doesn’t seem to be the case here as almost everyone had a similar max value.

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pdlpsher1
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by pdlpsher1

I haven't seen jagged power graphs from a Quarq, including from the two Quarqs I owned. With a simple Google I found the following. What I want to know is that if a PM has a sampling rate higher than 1hz, can I assume the data sent via ANT+ is smoothed? It would appear that the Quarq does this. Where can I find the sampling rate of a particular PM? Lastly, some PMs offer pedaling dynamics, which I presume requires a data recording frequency higher than 1hz. Would enabling the pedaling dynamics option offer an increase in data accuracy?

Quarq
Quarq has one of the highest sampling rates of any power meter, reportedly over 5000Hz (5000 times per second). But Quarq doesn’t have its own head unit so you’re limited to ANT+, which will only record and display data at 1Hz. That’s a lot of data going to waste right now, but it could be useful with a more advanced head unit in future.

P2M
How often we sample: We use a very high sampling rate of 50Hz, i.e. 50 measurements per second. This gives us very precise measurements and allows you to use oval chain rings without problems.

Rotor; from GP Lama's Lab
Accurate outside, reads a little high indoors. A number of us power meter propeller-heads noted this when performing comparative tests. Has an interesting 50Hz high-speed transmission mode which is only compatible when using their software indoors. Unit has a 200Hz sample rate at all times and is Q-Ring compatible. Rechargeable battery with a proprietary connector.

InfoCrank
It is not possible to achieve 0.5% accuracy in a power meter with fewer than 50 samples per rotation. InfoCrank’s 256 samples per second rate far exceed this requirement even at high cadence.

InfoCrank measures torque at 256 samples per second, so at 60 rpm, it samples 256 times per rotation, at 120 rpm, 128 times, and so on. With a low sampling rate, important torque information is not recorded, especially during the torque peak of the rider’s power stroke.

This has been put to the test: torque data of a track rider’s session was collected at 480 samples/sec, using local storage on the bike. After download, it was plotted using a discrete Fourier transform.

The data was then plotted again using the simplified algorithm implemented within InfoCrank’s firmware—the waveform is identical to the Fourier plot.

A sampling rate greater than 256/sec does not increase precision, requires more compute power (so more battery power), and requires more bandwidth than is currently available to transmit reliably to the head unit with no data

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by RyanH


arcatern wrote:
sounds like you've put a lot of different units through their paces.
what's your take on sigeyi axo, power2max (ng eco, if you wanna be specific), 4iii dual?
I've been meaning to borrow a Sigeyi from a friend to test. I have crank arms here for them. Power2max has always been the heaviest of the bunch so I've never bothered to own one. The new 4 bolt SL one is finally competitive with SRM/Quarq/Sigeyi on the weight front but I can't use MKV rings (103g with chainring bolts) with a 4 bolt PM.

I haven't tried 4iii.

If I wasn't a speedplay user, I'd try Favero or Garmin. I'll probably pick up a pair of Wahoo power pedals down the road so I can run them in comparison mode to my SRM.

Oh, and another "power meter" I have tried is my Wahoo Kickr which is utter garbage. It drifts up to 10% over the week. Sample size of one though.

TobinHatesYou
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by TobinHatesYou

pdlpsher1 wrote:
Sun Oct 16, 2022 4:48 am
I haven't seen jagged power graphs from a Quarq, including from the two Quarqs I owned. With a simple Google I found the following. What I want to know is that if a PM has a sampling rate higher than 1hz, can I assume the data sent via ANT+ is smoothed? It would appear that the Quarq does this. Where can I find the sampling rate of a particular PM? Lastly, some PMs offer pedaling dynamics, which I presume requires a data recording frequency higher than 1hz. Would enabling the pedaling dynamics option offer an increase in data accuracy?

Quarq
Quarq has one of the highest sampling rates of any power meter, reportedly over 5000Hz (5000 times per second). But Quarq doesn’t have its own head unit so you’re limited to ANT+, which will only record and display data at 1Hz. That’s a lot of data going to waste right now, but it could be useful with a more advanced head unit in future.

P2M
How often we sample: We use a very high sampling rate of 50Hz, i.e. 50 measurements per second. This gives us very precise measurements and allows you to use oval chain rings without problems.

Rotor; from GP Lama's Lab
Accurate outside, reads a little high indoors. A number of us power meter propeller-heads noted this when performing comparative tests. Has an interesting 50Hz high-speed transmission mode which is only compatible when using their software indoors. Unit has a 200Hz sample rate at all times and is Q-Ring compatible. Rechargeable battery with a proprietary connector.

InfoCrank
It is not possible to achieve 0.5% accuracy in a power meter with fewer than 50 samples per rotation. InfoCrank’s 256 samples per second rate far exceed this requirement even at high cadence.

InfoCrank measures torque at 256 samples per second, so at 60 rpm, it samples 256 times per rotation, at 120 rpm, 128 times, and so on. With a low sampling rate, important torque information is not recorded, especially during the torque peak of the rider’s power stroke.

This has been put to the test: torque data of a track rider’s session was collected at 480 samples/sec, using local storage on the bike. After download, it was plotted using a discrete Fourier transform.

The data was then plotted again using the simplified algorithm implemented within InfoCrank’s firmware—the waveform is identical to the Fourier plot.

A sampling rate greater than 256/sec does not increase precision, requires more compute power (so more battery power), and requires more bandwidth than is currently available to transmit reliably to the head unit with no data
All power meters perform filtering. They aren't measuring power after all, but calculating it based off torque (force) and cadence (speed). However there's no correlation between >1Hz sampling rate and jagginess. Your FIT file from a Garmin or Wahoo only records at 1Hz regardless of the device. You can easily confirm this by opening up your files in a FIT file editor / browser.

BTW here is my power plot from my Quarq. It's jagged, is it not?
Attachments
lowgap1.png

floriansantana
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by floriansantana

I just ordered a Sigeyi AXO PM from BikeInn since they had it in stock. Previously I ordered two PMs from Velowear and the were both Hardware Version 5. This one is Hardware Version 2.9. It also says that firmware version 1.99 is the latest one whereas the other two are at 4.020.

Does anyone know what’s the difference between these? Should I return the one I got and try to get the same hardware version 5?

Thanks in advance.
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oldmac
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by oldmac

floriansantana wrote:
Tue Oct 18, 2022 8:11 pm
I just ordered a Sigeyi AXO PM from BikeInn since they had it in stock. Previously I ordered two PMs from Velowear and the were both Hardware Version 5. This one is Hardware Version 2.9. It also says that firmware version 1.99 is the latest one whereas the other two are at 4.020.

Does anyone know what’s the difference between these? Should I return the one I got and try to get the same hardware version 5?

Thanks in advance.
Your new AXO with PM2.9 hardware version and 1.99 firmware version is the latest version power meter.
The Hardware Version 5 power meter is older than PM2.9 hardware version.
Sigeyi changes the hardware in the middle of this year.

floriansantana
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by floriansantana

oldmac wrote:
Wed Oct 19, 2022 4:38 am
floriansantana wrote:
Tue Oct 18, 2022 8:11 pm
I just ordered a Sigeyi AXO PM from BikeInn since they had it in stock. Previously I ordered two PMs from Velowear and the were both Hardware Version 5. This one is Hardware Version 2.9. It also says that firmware version 1.99 is the latest one whereas the other two are at 4.020.

Does anyone know what’s the difference between these? Should I return the one I got and try to get the same hardware version 5?

Thanks in advance.
Your new AXO with PM2.9 hardware version and 1.99 firmware version is the latest version power meter.
The Hardware Version 5 power meter is older than PM2.9 hardware version.
Sigeyi changes the hardware in the middle of this year.
Alright thanks for the clarification. That’s indeed a bit strange to make the newer one 2.9 instead of 5 but I’ll take it.
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kode54
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by kode54

Correct. I have an older PM and a newer one as well, confirming above reply. Doesn’t necessarily say it’s older but knows which firmware for old and new PM.
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by Aeo

There were also "old" power meters with Hardware Version 8 and 9
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cberg
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by cberg

On topic of power smoothing, I did a race that had a cobble section this year and every time we went over I got some pretty wild power spikes with my Sigeyi pm. I dont think I did more than 600 watts at any point over the cobbles but I got peaks of 11-1800 watts with measurements before and after being somewhat lower than I would expect. Never had this with my Quarqs, but then again I never rode them like that :)

MrRolandos
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by MrRolandos

I am considering purchasing an Sigeyi for my MTB. I got an Shimano XT M8100 crankset, should work with 4-104BCD I assume?

How would you guys rate the Sigeyi on MTB compared to the options we got these days? 4iii left, stages left, P2M are kinda my other options. I have a P2M on my roadbike, which works flawless. Would you guys say, readings are good? I read different kinda results here. But not sure if on MTB or road.

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gplama
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by gplama

Just insatlled one on my MTB about two hours ago. Should be out on it in the next few days with another meter to compare it to.

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