Well the good news is…you have a lot of options. I guess this is also the bad news as it can make deciding more difficult! 🙂 Ok, here goes:
Crankset Power Meter (Spider Based)
power2max ROTOR ALDHU Road Power Meter Crankset (staff favorite)
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 DA 9100 rings on it.
The Sigeyi power meter crankset is very similar to the power2max above. It is a spider-based power meter that measures power from both legs and will also serve as a direct replacement for a Shimano R9100 crankset. It is accurate to within +/-1.0%, is lightweight and features a rechargeable battery. However, it is a bit more affordable than the power2max.
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 chainrings on it or buy new ROTOR rings.
Like the power2max above, this is spider-based crankset and it’s a wonderful option as well. You would purchase the DFour Power Meter spider as well as Quarq DZero DUB crank arms. At $640, this is quite a bargain for a high-end power meter and carbon crankset. The power meter is also designed for use with Shimano DURA-ACE 9100 chainrings so you can use your current chainrings on it. However, unlike the power2max, you must change your bottom bracket. Specifically, the DFour requires a SRAM DUB Bottom Bracket. They are relatively inexpensive, but it does make installation a bit more involved.
Pros: Moderately priced, VERY reliable, measures both legs
Cons: Have to change your crankset
Crankset Power Meter (Crank Arm Based)
In addition to making left side crank arms for Shimano, 4iiii also makes complete dual-sided DA 9100 cranksets. With this power meter, you get a new Shimano crankset with a power sensor attached to the inside of the left and right crank arm. Therefore, they are able to measure power from both legs as well as tell you how much power each leg is producing individually.
Please note, as with the left side power meters above, you need to confirm you have 10mm of clearance between the left crank arm and the chainstay in order for the sensor to clear.
Pros: Measures both legs, provides independent left/right power
Cons: More expensive
Power Meter Pedals
Power meter pedals can be installed on any crankset. They are reliable, accurate, easy to install and can be moved between bikes. We carry every power meter pedal available including ones from Favero, Garmin, SRM/LOOK and Wahoo. This includes both single- and dual-sided versions as well as pedals for SPD-SL, LOOK Keo and Speedplay cleats.
Pros: Easy to install, works on any bike, can move from bike to bike, don’t have to change crankset