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 and Stages Cycling both make crank arm power meters for Shimano DA 9100.
These power meters measure left leg power and double 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.
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
Crankset Power Meter (Spider Based)
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.
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 $595, 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 and Stages also make complete dual-sided DA 9100 cranksets. With these power meters, 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. We have several models to choose from.
Pros: Easy to install, works on any bike, can move from bike to bike, don’t have to change crankset