Currently, there are indeed a few options for a Shimano Ultegra R8100 crankset. However, this groupset is still new and we expect there to be more options available as we get into 2022 and other power meters that fit this groupset are released.
Left Crank Arm Power Meter
Stages Shimano Ultegra R8100 Power Meter
With the Stages left side power meter, you simply swap out your current left crank arm for the new power-equipped one and you are good to go.
Stages Shimano Ultegra R8100 Power Meter
Please note, these power meters attach a sensor to the inside of the left crank arm. On some bikes, there is not enough room between the left crank arm and the chainstay for the sensor to clear the frame. Therefore, you should make sure you have at least 10 mm of clearance for Stages power meters. Also, please make sure that you don’t have a bottom bracket mounted rear brake (used on some aero and TT bikes). Please refer to the image below.
Pros: Affordable, easy to install, don’t have to change crankset
Cons: Measures left leg power only
Crankset Power Meter (Spider Based)
power2max ROTOR ALDHU Road Power Meter Crankset (our best recommendation)
This is a new crankset (power meter spider, crank arms and spindle), excluding chainrings. power2max makes wonderful power meters. They measure both left and right leg power, are reasonably priced and are as good as it gets in terms of reliability. If you select the 24MM spindle option, it will fit your current bottom bracket exactly like your Shimano crankset (no need to change bottom brackets). In addition, if you select the Shimano 4-Bolt spider, you can even use your Shimano R8100 rings on it.
power2max NGeco ROTOR ALDHU Road Power Meter Crankset
ROTOR INspider ALDHU Road Power Meter Crankset
This too is a new crankset (power meter spider, crank arms and spindle) and can be purchased with or without chainrings. The INspider measures both left and right leg power, comes in a variety of crank arm lengths and can be set up in a 1X or 2X chainring configuration. This power meter can also be purchased with a 24MM spindle so it will fit your current bottom bracket without any changes. You can use your current Shimano 8100 chainrings on it or buy new ROTOR rings.
ROTOR INspider ALDHU Road Power Meter Crankset
Pros: Moderately priced, VERY reliable, measures both legs
Cons: Have to change your crankset
Crankset Power Meter (Crank Arm Based)
While currently not available, we expect 4iiii and Stages Cycling to also release dual-sided cranksets for Shimano R8000 in early to mid-2022. We will update this article as soon as we have them.
Pros: Measures both legs, provides independent left/right power
Cons: More expensive
Power Meter Pedals
Power meter pedals can be installed on any crankset. We have several models to choose from.
Pros: Easy to install, works on any bike, can move from bike to bike, don’t have to change crankset
Cons: None