There are several power meters that will work on Specialized cranksets:
Spider Power Meters for Specialized Cranks
These are power meter power meters are compatible with Specialized S-Works carbon cranks. The Quarq is compatible with cranks from 2013-current, whereas the power2max fits all models. They come in both 110 and 130 BCD options and work with traditional 5-bolt chainrings from most manufacturers. In addition, because they are spider-based power meters, they measure power from both legs.
Pros: Moderately priced, VERY reliable, don’t have to change crankset, measures both legs
Left Crank Arm Power Meter
This Stages crank arm will work on 2017 and newer Specialized S-Works Road cranksets with Spindle F. This power meter measures left leg power only.
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: Easy to install, don’t have to change crankset
Cons: Measures left leg power only
Power Meter Pedals
Power meter pedals can be installed on any crankset. This is a very popular power meter type as they fit any bike, are easy to install and can be moved from bike to bike if necessary. We carry power meter pedals from Favero, Garmin, SRM/LOOK and Wahoo. This includes pedals for SPD-SL, LOOK Keo as well as Speedplay cleats.
Pros: Easy to install, works on any bike, can move from bike to bike, don’t have to change crankset