There are several power meters that will work a Shimano SLX MTB crankset. Please note that some of these power meters fit SLX 7000 only, while others fit SLX 7100 only. SLX 7000 and 7100 use different spline depths and interfaces, so it’s important you select a power meter that is compatible with your crankset.
Left Crank Arm Power Meter
For Shimano SLX 7100 cranks:
These power meters are left side crank arms. You simply use them in replace of your existing left crank arm. Installation is quick and easy.
Please note, these are Shimano XT arms – so therefore the color of these crank arms won’t match your SLX exactly (a cosmetic issue only), but most customers are ok with this.
4iiii PRECISION Power Meter For Shimano XT M8100/8120

4iiii PRECISION Power Meter For Shimano XT M8100/8120
Stages Shimano XT M8100/8120 Power Meter

Stages Shimano XT M8100/8120 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 and 4iiii PRECISION 2 power meters and 8 mm of clearance for 4iiii PRECISION 3+ 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
Right Crank Arm Power Meter
For Shimano SLX 7100 cranks:
Stages Shimano XT M8120 Driveside Power Meter
Some bike frames are not able to fit a left side crank arm power meter like the ones above as there is not sufficient frame clearance for the power sensor. However, Stages Cycling makes a right side version that will fit all frames. Please note that this is a XT crank arm (Stages doesn’t make SLX right arms), however it will fit your SLX perfectly – the color of the XT arm is just a bit different. Also, please note the right side versions cost a bit more than the left side crank arms, but this is because they also come with new chainrings.

Stages Shimano XT M8120 Driveside Power Meter
Pros: Affordable, easy to install, don’t have to change crankset
Cons: Measures right leg power only
Spider Power Meter
For Shimano SLX 7100 cranks:
power2max NGeco Shimano MTB Power Meter
These power meters are compatible with Shimano MTB direct mount cranksets using a 1x chainring such as the M7100. In addition, because they are spider-based power meters, they measure power from both legs.

power2max NGeco Shimano MTB Power Meter
Sigeyi AXO Shimano MTB Power Meter
The Sigeyi AXO Shimano MTB power meter is also compatible with Shimano MTB direct mount cranksets such as the M7100. They are spider-based power meters and measure power from your left and right legs.

Sigeyi AXO Shimano MTB Power Meter
Please note, the power2max and Sigeyi use a 104 BCD chainring configuration. So you will need a 104 BCD MTB chainring as well.
Pros: Moderately priced, VERY reliable, don’t have to change crankset, measures both legs
Cons: None
Power Meter Pedals
For any Shimano SLX cranks:
MTB power meter pedals are also a great option as they can easily be installed on any MTB crankset and can be moved between bikes if necessary. We carry every option available including the Favero PRO MX, LOOK X-Track, Garmin Rally XC, SRM X-Power and SRM X-Power Flat Pedals.
Pros: Easy to install, works on any bike, can move from bike to bike, don’t have to change crankset
Cons: Some versions are pricey
Crankset Power Meter
Stages Shimano XT M8120 Dual-Sided Crankset
Of course, you can also choose to replace your crankset entirely for a new one. These cranksets are move expensive then a left or right side crank arm, but they measure power from both the left and right leg. They also come with a new set of chainrings.

Stages Shimano XT M8120 Dual-Sided Crankset
Pros: Accurate, reliable, measures both legs
Cons: More expensive, more work to install