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:
Left Crank Arm Power Meter
4iiii makes a crank arm power meter for Shimano DA 9100. This power meter measures left leg power and doubles the value to determine your total power. You just swap out your current left crank arm for the new power-equipped one and you are good to go.
4iiii PRECISION Power Meter For Shimano DURA-ACE 9100
Please note, this power meter attaches 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 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
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.
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 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.
4iiii PRECISION PRO Shimano DURA-ACE 9100 Dual-Sided Crankset
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