Dual side power meter for Shimano 105

Quarq Dfour PM crankset and move the 105 chainrings across? Very consistent and reliable power and would guess similar price top the other options you’re looking at. Would mean changing your bottom bracket as well though.


Power2Max makes a great PM that’ll work with your 105 rings and Shimano bottom bracket.

There have historically been accuracy issues with right side power meters due to the way Shimano builds the cranks. Not sure if they’ve been sorted out, but I wouldn’t want to take the risk for that kind of money.


Not sure how these would work for you but,…

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Get the XC100s.

Love mine. They’ve been beat to hell with zero issues. Three seasons of XC racing and three BWRs.

Dual sided power meters are totally overrated.

Also, unlike cranks, you can actually calibrate your power pedals to match your trainer. It takes some trial an error but you basically fudge the crank length in your head unit. So let’s say your cranks are 172.5mm. Your power meter reads high, so you now you adjust the crank length value to 171mm or 170mm. Bingo.

I’d also recommend the power2max NGeco. I use it with a shimano 105 groupset and it is fantastic.

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At the risk of opening a can of worms, you won’t know if you have a significant L/R imbalance unless you measure total power. I run Assioma Duo-Shi now and found I typically have a 52% L/48% R balance. My prior rides on left side PM’s were therefore reading high and I was blissfully unaware thinking my FTP was higher than it was :rofl:

I’d argue that total power is preferable, which you can get from spindle or dual sided PM’s. Nothing wrong with single sided PM’s if that’s your main source of power or if you don’t have an imbalance.

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I’d say dual sided can be very useful for some people. E.g. I’ve had various injury issues over the years including a herniated disc which have affected my L:R balance. When I’m healthy, fit and on top of my exercises I’m usually in the 48:52 to 50:50 range. But if I’ve got a niggle or am tired it’s not uncommon to see 45:55 and at times following a crash or injury I’ve had rides at 42:58.

Having dual sided means I’m at least aware that something is out of whack and needs working on, and that my power measurements are accurate regardless of L:R imbalances. Single sided for me would hugely underestimate my power at times. Even my “normal” variation of 2-3% difference in contribution from each leg from one ride to the next would double up to 4-6% variations in recorded power which is quite a lot. No idea how common it is for people to have the same sort of variability I do, could be I’m a complete outlier.


Thank you very much for all the input!

The Power2Max seems to be a bit pricy (890€), especially if I am planning to change my bike in 1-2 years. For +50€ I could get the Garmin XC200.

The Quarq DFour spindle seems to be the more budget friendly option (330€ for the spider, 530€ with a full crankset) (suggested by @cartsman)

Right now I am leaning towards Assioma DUO-Shi + SPD pedals (which seems to work fine, if you can deal with the q-factor).
It is not cheap (650€) but it would give me all the flexibility in the future.

I picked up the Duo Shi last fall and have been really impressed. I thought I’d only use them on my gravel bike, but in the past two weeks I’ve swapped them onto a backup road bike and a backup MTB. Really handy and adaptable, having power meter pedals.

I put the SPD pedal bodies on and they’ve been great.


Which SPD Pedal did you use? Would you use it again?

Im testing Inpeak Twin2 now, but on Shimano R8200 crankset and results may be worse, than on 105. 105 crankset aren’t vulnerable in matter of metering inaccuracy, they are constructed in different way, than Ultegra/DuraAce (tested with Ronde on R7000/R8000 I own). If you need to buy crankset, buy 105 with Inpeak. If you have crankset, buy Assioma Duo powermeter.

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You wouldn’t need to buy new shoes if converted them to SPD as @wattage_narco suggests. There’s loads of videos on the hack, this is one of them.


@tadzikpl This is good to know! Thank you

I just bought a pair of Assioma DUO-Shi and Shimano SPD pedals. Will try this first, if it doesn’t work I think I will get the 4iiii Precision 3 (one sided) and then upgrade to two sided with a new bike.

@HLaB The original hack is not required anymore if you buy the Assioma DUO-Shi (it’s just the spindle, but more q-factor). A couple of Shimano SPD pedals work (while not officially supported), I created an overview here


Sorry I copied the wrong vid but it sounds like you are sorted :+1:

Favero Assioma Shi - How To Swap onto Shimano Pedal - YouTube Edit thats still not the right one I saw yesterday which put SPDs on a shi

Thanks for sharing! Well, the process should be the same for the SPD pedals!

The Assioma Shi should arrive Wed or Thu - then I know if it works or not :slight_smile:

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The black ones - M520s.

The spindles should look like these.

Not like these.

For example, I have a new set of XTR pedals, and the spindles look like the second link. They won’t work with the Assiomas (at least the Duo-Shis).

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If you choose the cheapest Power2Max NGeco, you can get it for 590€: NGeco Road power2max GranFondo Set – power2max

If you want a Rotor crank set or other options, it gets iteratively more expensive. I’m using the Rotor3D24 crank set which used to ship for 680€. The cheapest Rotor option now is a bit more expensive.

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I have excellent agreement with quarq and power2max spider powermeters. Much less agreement with pioneer and stages single arm powermeters. A buddy has single side garmin mtb and it seems way way off. Might be defective though. It’s just not in the same ballpark in our tests.

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Thank you again for all the input! My Favero Assioma Duo-Shi arrived today. I installed them with PD-M520 pedals. (please see my post in the other thread for more details)

First impression is great, I will test them over the next couple of days.


You will like the Assiomas. They are by far the best PM for the best price I’ve ever seen.

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