Power meter comparison – Rotor 2inPower vs. Shimano Dura-Ace FC-R9100-P

Shimano FC-R9100P
Shimano FC-R9100P

I have two power meters, a Rotor 2inPower and a Shimano Dura-Ace FC-R9100-P. The first one I use since two years, the second since six months. When choosing a power meter the following criteria is important for me:

  • measurement accuracy
  • left/right measurement
  • support for ANT+ and Bluetooth
  • easy rechargeability of the battery
  • easy installation
  • unobtrusive design


2inPower and FC-R9110-P both fulfill these requirements. In this blog post I will compare the two products. However, it’s more an experience comparison from an end-user’s perspective rather than a full-fledged product comparison.

2inPower FC-R9100-P
Installation Very easy installation, literally the same installation process as the installation of a normal crank set. Moving the power meter to another bike is a breeze.
However, 2inPower needs a UBB30 bottom bracket. I you have Shimano Hollowtech II or any other standard, you will need to buy and install a new bottom bracket.
Installation is more complicated. You will need to install a magnet on the frame, fiddle with a tiny cable/plug and with Shimano FC-R9100-P specific tools. Moving the power meter to another bike means that you will first need to buy the magnet and then repeat the installation process on the other bike.
R9100-P works with any Hollowtech II bottom bracket.
Setup/calibration iOS/Android app, macOS/Windows app. Note: I never managed to install and run the macOS app on my MacBook Pro. This software is completely useless.

Calibration can also be done via bike computer (e.g. Garmin Edge, etc.). Calibration needs you to unclip from your pedal, start the calibration and then manually turn the crankset twice.

iOS/Android app or via Shimano E-tube project software for Windows.

Calibration can also be done via bike computer (e.g. Garmin Edge, etc.). Calibration only requires you to unclip from your pedals and then start the calibration. That’s it.

Charging Claimed battery life is 250 h. I don’t know how this number was derived. But I had to recharge it more often than my Di2 battery which has a durability of about 1500 km or 60 h. If your battery is empty and you want to go out for a ride, 5 to 10 minutes of recharging will be sufficient for a ride.
An additional USB charging cable cost USD 15.00.
The plastic cover of the charging plug is one of the most stupid solutions I have seen so far. The construction will guarantee that it will eventually be lost. So better organize a replacement before you loose it.
Claimed battery life is 300 h. I don’t have enough ride time with this power meter to verifiy that.

An additional USB charging cable costs around USD 80.00. Insane!!!

Shifting performance Shifting performance is probably the weakest point of this product. Chain drops can happen from time to time. However, it’s not too bad, but probably somewhere around the shifting performance of Shimano 105. Excellent shifting performance, as expected from a Dura-Ace crankset when using one of the Shimano recommended chain ring setups (also see chapter ‘Shifting performance with 52/34 chain rings’ at the end of this blog post).
Chain rings Rotor is well known for it’s oval chain ring named Q-Rings. Shimano doesn’t produce oval chain rings. But you can buy oval chain rings from third party suppliers such as Rotor, absoluteBLACK, Wolftooth, etc.
Look & feel I like the design of the crankset. I especially like the red anodized aluminium parts. They give a very nice finish to the product. Furthermore you have many options to pimp your crankset design by using different chain rings, e.g. the Rotor Aero chain rings. The FC-R9100-P perfectly fits with the other products of the Shimano 9100 group set. The glossy black finish just looks nice on any bike.
Price around USD 1’400.00 around USD 1’400.00


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After about 1.5 years of usage the power meter started to show insanely high Watt numbers, and often the left/right balance was absolute nonfactual (up to 30% difference between left and right). Furthermore I wasn’t able to start the calibration process from my Garmin unit anymore. I always had to use the Rotor iOS app. However, a calibration before each ride seemed to solve the problem.

After some online research I decided to perform a software update. Even tough the update process looked easy on the paper, it took me three hours to make it happen. I had to try various combinations of computers and software until Rotor’s crappy software finally managed to perform the update.

However, since the software update the above mentioned problems have disappeared. I don’t have to calibrate my power meter before each ride anymore and the data seems to be alright again.


To make a long story short, my FC-R9100-P refused to transmit data after only 5 months of usage. My local Shimano service center told me that the power meter can not be repaired. After being on a waiting list for about four weeks I finally received a replacement which so far works without problems.

Shifting performance with 52/34 chain rings

My preferred front chain ring setup is 52/34 tooths. However, at least Shimano does not officially support this combination. Only 52/36, 50/34, etc. is supported by Shimano. Nevertheless, I use 52/34 with my Shimano Powermeter. But the shifting performance of the front chain rings is clearly not optimal with this setup. It sometimes takes more than a full turn of the crank till the chain has switched the chain ring, especially when switching from the small to the big chain ring. However, for me this not a big issue. I often do not shift more than ten times between my two chain rings even during rides longer than 100 km.

A completely different story with Rotor. I don’t feel any decrease in the shifting performance when using a 52/34 chain ring combination instead of 52/36. I also have to say that I didn’t find any chain ring combination recommendation from Rotor. So I don’t know whether they officially support 52/34 or not. But the shifting performance remains the same as with 52/36.


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