The DFour91, like its sibling, the DFour, uses the same meter as the DZero model, but drops a bolt to fit a Shimano drivetrain-- specifically, Shimano Dura-Ace 9100 . Unlike its predecessor, the DFour, the D9100 is not compatible with Dura-Ace 9000, Ultegra, or 105 groupsets, though it is able to run Ultegra R8000 chainrings. With the exception of the difference in compatibility, the DFour91 includes all of the technology of the DZero packed into its spider, most importantly the power meter itself. The power meter saw some hefty reworking, with Quarq claiming 150 documented improvements, asserting leaps and bounds of advancement above previous models, with the most significant enhancements made to the strain gauges and measurement circuitry in the heart of the meter. As in previous models, the DFour91 incorporates five meticulously placed strain gauges throughout the spider, designed to measure how many Newton Meters you're putting out when you hammer on the pedals. And it still incorporates the same level of claimed accuracy at +/- 1. 5%, keeping it 0. 5% more accurate than most meters. One of our favorite features, though, is that the new design doesn't require as much correction in order to maintain accuracy through massive temperature ranges, allowing things to work smoother when the mercury drops. This means that the DFour91, like the DFour, is better at rationing battery life through changing weather, but when the battery does die out, it's still easy to change without tools or tedious procedures. Quarq's 10K Dynamic temperature compensation technology graces us with its presence in the DFour91, alleviating us from the stress of constant mid-race zeroing when the temperatures fluctuate on long alpine climbs, or early morning to warm afternoon race days. While making corrections may seem like they come at a minuscule cost of coasting for a couple of seconds, it can make all of the difference between the podium and sidewalk come race day. Not to mention the ...
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Quarq DFour91 Power Meter Crank Arms - GXP
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