Shimano GRX Power Meters Overview
You have a few great options for your Shimano GRX crankset based on your budget and if you are comfortable changing out your crankset. Both 4iiii and Stages make a Shimano GRX RX810 power meter. With this type of power meter, you swap out your current left crank arm for the new power-equipped version. power2max also makes spider-based cranksets for GRX. Their 24MM version is a direct replacement for your Shimano GRX. The power2max measures power from both legs.
Left Crank Arm Power Meter
Both 4iiii and Stages make a Shimano GRX RX810 power meter which is compatible with all Shimano GRX cranksets including GRX RX600. With this type of power meter, you swap out your current left crank arm for the new power-equipped version. These power meters are affordable and easy to install. The trade-off is they only measure left leg power.
Please note, whenever you are installing a left side power meter crank arm, you need to confirm you have 10mm of clearance between the left crank arm and the chainstay in order for the sensor to clear. Please see the image below.
Pros: Affordable, easy to install, don’t have to change crankset
Cons: Measures left leg power only
Spider-Based Power Meter
The power2max NGeco ROTOR ALDHU 24MM Crankset is a direct replacement for your Shimano GRX crankset. The power meter uses the same 24MM spindle as your GRX crankset, so this power meter fits your current bottom bracket without any changes. This makes installation very easy. Even better, the power meter gives you a narrow road Q factor vs. the slightly wider Q factor inherent in GRX cranks and allows you to run a 1x or 2x chainring set-up.
Pros: Moderately priced, VERY reliable, measures both legs