Shimano

Dura-Ace FC-R9100-P Power Meter Crankset

Using a powermeter has been a revelation in training over the past 10 or so years. Compared to using a heart rate monitor, wattage as a metric is more specific to the effort and removes many variables that could disrupt proper training on a given ride. Of course, these numbers are only as good as the device they are coming from and knowing the precision that Shimano instills on its premium products, we know the power measurement readings are up to the accuracy that professional cyclists demand. The unit itself is very small with a strain gauge inside the spindle, a couple of sensors on the backside of each crankarm for true dual-sided power reading, and an antenna/charging port sending and receiving Bluetooth LE and ANT+ signals, nestled between two arms of the spider.

We like this design because 1) you can easily change rings without having to recalibrate the meter, 2) the sensors are small enough that they have the clearance to not interfere with bottom bracket/chainstay direct mount brakes. The sensors are tied together requiring only one intergraded, Li-ion rechargeable battery to provide roughly 300 hours of use before needing to be recharged. Shimano went to great lengths to develop its own strain gauges for measuring data. Sensors on both arms tie into another gauge safely hidden inside the spindle that quickly detects any resistance and with some math, converts the applied force and velocity into a measurable metric, wattage. Shimano uses software that automatically compensates for temperature and elevation changes, so the reading has the same +/- 2-percent accuracy in your driveway at the start of a chilly ride in the fall as it does on the top of Pike's Peak in the summer.