Shimano R9100-P Powermeter

[TobinHatesYou]

No, ruklaw, you’re not getting it. You can definitely guarantee 100% right balance by, gasp, unclipping the left shoe and pedaling with just the right leg.

And also no, there are no appreciable hysteresis losses between pedals and cranks. If there were 10 watts worth of losses between the two, your cranks would get quite hot to the touch. Jesus. For all intents, a crankarm and pedal are a rigid structure.

You really don’t know anything, don’t you?

Also GPLama wasn’t the first to report on this. AFAIK, Ben Delaney did in his BikeRadar review (now at VeloNews.) I see no issue with Lama’s testing method, especially when he’s been able to confirm L/R balance uniformity by testing multiple pedals in single-leg drills. Go away.

He didn't unclip the left shoe and pedal with just the right leg though did he? Nowhere does he say that. Read it again.

Seriously, if you want to do the tests show me. If you know someone who did, show me.

He divided the Erg mode setting by two and used that as a baseline. That is very very different.

The guy above apparently did it with a pioneer, but that's a different thread.

He’s done it before in testing with those pedals and other pedals so they are a known quantity. They represent his baseline for a reason. They work well, really well. Also regardless of the right-only data, he has the full power data and if the Assioma Duo data adds up to 250W while the cranks all add up to 239W, then you can be pretty sure something is up.

Again, you can't seem to comprehend that a dozen different models were all discovered to read low in Lama’s tests, including the R9100-P. You also clearly don’t understand that his testing history has validated the accuracy of his pedals and various other power meters in his stable.

[Sockman]

So if we believe the gplama testing (which I do), what's the approx percentage the right side of any 9100 based pm is off by?

Sounds like I just found some free watts

[billendk]

When i compare my shimano powermeter to my tacx neo, the results is within 5w. I can live with that


Sent from my iPhone using Tapatalk Pro

[ruklaw]

Also GPLama wasn’t the first to report on this. AFAIK, Ben Delaney did in his BikeRadar review (now at VeloNews.) I see no issue with Lama’s testing method, especially when he’s been able to confirm L/R balance uniformity by testing multiple pedals in single-leg drills. Go away.

He didn't unclip the left shoe and pedal with just the right leg though did he? Nowhere does he say that. Read it again.

Seriously, if you want to do the tests show me. If you know someone who did, show me.

He divided the Erg mode setting by two and used that as a baseline. That is very very different.

The guy above apparently did it with a pioneer, but that's a different thread.

He’s done it before in testing with those pedals and other pedals so they are a known quantity. They represent his baseline for a reason. They work well, really well. Also regardless of the right-only data, he has the full power data and if the Assioma Duo data adds up to 250W while the cranks all add up to 239W, then you can be pretty sure something is up.

Again, you can't seem to comprehend that a dozen different models were all discovered to read low in Lama’s tests, including the R9100-P. You also clearly don’t understand that his testing history has validated the accuracy of his pedals and various other power meters in his stable.

I've just had a look at the BikeRadar review. Ben is completely happy with the total power data, but the left right balance seems off. Basically the same as Ray Maker found.

I can live with that!

GPLama seems to be the only reviewer who has found fault with the total power readings of the R9100-P -it sounds to me like he had/has a duff unit. It's hard to say much more than that as his data seems to be in a youtube video, and I can't be arsed to scrutinize the results in a non readable format.

Now, I'm not for a moment saying that crankarm PMs based on current Shimano cranks don't give iffy results for L/R - it wouldn't surprise me in the least if they are fiddling it slightly, for the sake of a more accurate total power measurement - that would seem reasonable to me - there is scope for a slightly fiddled result being better than those of a left side only power meters, which are themselves good enough for many thousands of riders out there.

What I don't like is the click-bait sensationalism of it, and that the only table of data comparing the results is against a baseline that is meaningless - percentages should have been calculated against the pedals if they are a trusted source of power, not the imaginary 125w.

And I do find it amusing that he rates the cheap and cheerful Xcadey power spider as a 'Yes, assuming it's correctly calibrated from the factory' - bit of a coincidence that he had to turn it up to 105% to match his pedals and turbo isn't it? I mean we've now got all these shimano cranks and the xcadey that read a bit low on his setup - or does his setup read a bit high?

I'm also slightly cautious of Keith Wakeham as a source. He is also producing click-bait headlines to drive traffic (because who is going to watch a video about a power meter that works OK despite technical challenges?), and while he worked on the early 4iiii models, he hasn't worked there for years - who knows how amicable his departure was?

Seriously, if you have compelling evidence that the R9100-P is not reliable in total power readings, I want to see it - but the overwhelming body of evidence seems to rate it fine.

[Unniti]

Even the bikeradar review you mentioned clearly shows that the right side underreports. And it seems like they've increased the left side power at Shimano to compensate for that. Left side reads 155 W compared to 150 W control and right side reads 145 W compared to the same 150 W control.

[ms6073]

When i compare my shimano powermeter to my tacx neo, the results is within 5w. I can live with that

I also see similar results in Rouvy after a power based workout, a little more discrepency when riding a video but as you said, still nothing I cannot live with.

[TonyM]

I also see some difference between my Tacx Neo and my 2 Dura Ace powemeters (and my P2M) but at my level I can live with that....

[BigCol]

Just to chip in - i have a shimano R9100-P, 2x9000 series Pioneer, 1 x 9100 series pioneer and a power2max. I also have an elite drivio 2 smart turbo!

I've experimented with most of the PMs over the years, including one-legged pedalling at powers from 100-200 Watts for around 1 minute to look at accuracy etc (the elite being +/-0.5%). Interestingly most of the PMs I've done this with are within 1-2% of each other and the elite with the exception of the 9100 series pioneer where the right side reads 8.7% low! I correct this in the pioneer head unit so my data is not affected. I've not tried it yet with the shimano PM - maybe I should to see how it gets on.....

Col.

OK - how does the total data compare between the Pioneer/Shimano and the turbo? Did that match at least?

I've not tried the shimano but the pioneer was out as a total by 50% of the 8.7% error (i'm around 51/49). The shimano out of the road gives very credible numbers so I suspect it might be quite good. When I get chance i'll hook the bike up to the Elite and have a look at some one legged pedalling with the shimano!

Thanks Col, I would really appreciate that. I've got a great offer on the R9100P from a trade contact and I'm tempted!

So he's the results!!!!!

Both feet clipped in, pedalling normally, Elite set to 250W rode for over a minute and took average of centred 1 minute block.
Result from R9100-P = 254W.

Left foot only clipped in, Elite set to 150W rode for around a minute and took average of centred 45 second block
Result from R9100-P = 156W (98.2/1.8 L/R balance)

Right foot only clipped in, Elite set to 150W rode for around a minute and took average of centred 45 second block
Result from R9100-P = 146W (2.12/97.88 L/R balance)

Pretty good numbers really, no issue on the right hand crank like my pioneer. Interesting that it reads some power from a crank I'm not even clipped into. Wonder if this is their 'algorithm', hard to believe it would be the intertia of the crank! Overall good enough for me to use and within the 1-2% of my other PMs......

[bilwit]

the L/R discrepancy is interesting and as always, you should expect ~3% difference between a crank based PM and the trainer to account for drivetrain losses

[TobinHatesYou]

the L/R discrepancy is interesting and as always, you should expect ~3% difference between a crank based PM and the trainer to account for drivetrain losses

More like 2% unless you are severely cross-chained. Oddly, my trainer (Hammer) does not report This difference. It is generally within 1W of my other two concurrently used power sources, so there is probably some “fudging” going on.

[TobinHatesYou]

OK - how does the total data compare between the Pioneer/Shimano and the turbo? Did that match at least?

I've not tried the shimano but the pioneer was out as a total by 50% of the 8.7% error (i'm around 51/49). The shimano out of the road gives very credible numbers so I suspect it might be quite good. When I get chance i'll hook the bike up to the Elite and have a look at some one legged pedalling with the shimano!

Thanks Col, I would really appreciate that. I've got a great offer on the R9100P from a trade contact and I'm tempted!

So he's the results!!!!!

Both feet clipped in, pedalling normally, Elite set to 250W rode for over a minute and took average of centred 1 minute block.
Result from R9100-P = 254W.

Left foot only clipped in, Elite set to 150W rode for around a minute and took average of centred 45 second block
Result from R9100-P = 156W (98.2/1.8 L/R balance)

Right foot only clipped in, Elite set to 150W rode for around a minute and took average of centred 45 second block
Result from R9100-P = 146W (2.12/97.88 L/R balance)

Pretty good numbers really, no issue on the right hand crank like my pioneer. Interesting that it reads some power from a crank I'm not even clipped into. Wonder if this is their 'algorithm', hard to believe it would be the intertia of the crank! Overall good enough for me to use and within the 1-2% of my other PMs......

So it’s reading 146W total despite attributing 2.12% to the left crank via coupling. This means the right crank is actually reading 142.9W. That’s perhaps acceptable in a vacuum, but there are plenty of other PMs that are actually accurate...and cheaper. When I engage in single leg pedaling on my true dual-leg PMs, the readings are 100-0 or vice-versa.

[ruklaw]

PMs that have more accurate dual sided readings and are cheaper than the R9100-P - which are those then?

Basically the Favero Assioma and the Powertap P2s?

Street price difference really isn't that much nowadays (as with most Shimano stuff, the RRP counts for very little), and if you happen to want a set of Dura Ace Cranks anyway the price difference is arguably in favour of the cranks.

There's also the added cost of cleats if you want to use more than one pair of shoes... the added risk of killing your pedals in a crash... servicing cost for pedal bearings down the line... 2 years of warranty vs 3 with the dura ace....

The Quarq and Power2Max are outright cheaper but they don't have dual sided readings.

And what if you don't want to have to change your pedal system? I run two bolt (most of my miles are stop start commuting and I would wear out road cleats/shoes in no time) so current pedal systems are pretty much a non starter, although I see SRM now have an (expensive) SPD option, and IQ2 have one coming although who knows how accurate that will be

[BigCol]

I've not tried the shimano but the pioneer was out as a total by 50% of the 8.7% error (i'm around 51/49). The shimano out of the road gives very credible numbers so I suspect it might be quite good. When I get chance i'll hook the bike up to the Elite and have a look at some one legged pedalling with the shimano!

Thanks Col, I would really appreciate that. I've got a great offer on the R9100P from a trade contact and I'm tempted!

So he's the results!!!!!

Both feet clipped in, pedalling normally, Elite set to 250W rode for over a minute and took average of centred 1 minute block.
Result from R9100-P = 254W.

Left foot only clipped in, Elite set to 150W rode for around a minute and took average of centred 45 second block
Result from R9100-P = 156W (98.2/1.8 L/R balance)

Right foot only clipped in, Elite set to 150W rode for around a minute and took average of centred 45 second block
Result from R9100-P = 146W (2.12/97.88 L/R balance)

Pretty good numbers really, no issue on the right hand crank like my pioneer. Interesting that it reads some power from a crank I'm not even clipped into. Wonder if this is their 'algorithm', hard to believe it would be the intertia of the crank! Overall good enough for me to use and within the 1-2% of my other PMs......

So it’s reading 146W total despite attributing 2.12% to the left crank via coupling. This means the right crank is actually reading 142.9W. That’s perhaps acceptable in a vacuum, but there are plenty of other PMs that are actually accurate...and cheaper. When I engage in single leg pedaling on my true dual-leg PMs, the readings are 100-0 or vice-versa.

I got mine for a really good price at the time luckily. The 9100P is a physically neat and tidy package, I like to have a shimano DA crank to match the rest of my bike..... and the left sensor clears the chainstay mounted direct mount shimano brake on my Scottt TT bike which is handy (pioneer sensor clashes!). The total power always seems very close, but L/R stuff is definitley very odd on this one!

Not sure if I would get one again if I was buying again. My preference is pioneer as you get a much richer data set with their head unit, and again if you use their head unit any slight error relaive to other PMs you own can be adjusted out by calibrating on my Elite! The 9000 series pioneer were bob on, but the 9100 needed a significant correction. Pioneer are doing some cracking deals now though - selling stock after the shimano buy out!

personally I wouldn't go for pedal PMs - high risk of damage in a crash and potential to 'wear out' eventually. Friends who have Vector 3s and powertaps have had no end of issues too which put me off......

[TobinHatesYou]

PMs that have more accurate dual sided readings and are cheaper than the R9100-P - which are those then?

Basically the Favero Assioma and the Powertap P2s?

Street price difference really isn't that much nowadays (as with most Shimano stuff, the RRP counts for very little), and if you happen to want a set of Dura Ace Cranks anyway the price difference is arguably in favour of the cranks.

There's also the added cost of cleats if you want to use more than one pair of shoes... the added risk of killing your pedals in a crash... servicing cost for pedal bearings down the line... 2 years of warranty vs 3 with the dura ace....

The Quarq and Power2Max are outright cheaper but they don't have dual sided readings.

And what if you don't want to have to change your pedal system? I run two bolt (most of my miles are stop start commuting and I would wear out road cleats/shoes in no time) so current pedal systems are pretty much a non starter, although I see SRM now have an (expensive) SPD option, and IQ2 have one coming although who knows how accurate that will be

Also the Vector 3s. Any Shimano crankset from the previous generation.

In 4 years of owning pedals (V2, V3, Assioma) I have tried very hard to kill them in crashes. I have not succeeded. You can also keep “adding” these hidden costs to the pedals, but all pedals need new bearings over time. All cyclists need new cleats over time.

Most of you miles are stop-start commuting, so why do you even need an R9100-P? Besides, if you are okay with the inaccuracy, why would you choose the R9100-P over the Stages, 4iiii, Pioneer, etc. They’re street prices are even cheaper.

Keep grasping at straws though.

[ipenguinking]

i chose R9100-P for the following reasons: asthetic because it looks very good with 9150 group on my bike; reliability because it's made by Shimano; price because it's a lot cheaper than SRM on my previous bike. On top of that I would not ride anything other than SPD-SL. My unit is actully one of the first units arrived the US and it hasn't let me down for over 2 years. Data is consistant. No drop out. Battery lasts a long time per charge.