SHIMANO DURA-ACE R9100-P
> Shimano releases its debut power tool
THE LONG-AWAITED POWER METER FROM Shimano delivers the Japanese brand’s typical consistency and high-end finish. But although the R9100-P proved consistent in total wattage readings, a few issues prevent it from earning top marks.
Checking power meter accuracy is tricky, so we run three meters simultaneously on one bike, recording each ride’s readings on each device and overlaying the data for comparison. On our first ride using the R9100-P its readings practically mirrored those of the Garmin Vector 3 pedals we were running. It displayed similar levels of accuracy in further testing alongside a Powertap hub.
The fly in the ointment is the left/ right balance being slightly off. Shimano initially blamed the firmware programmed into the R9100-P but an update did nothing to rectify the issue. Further investigations, which amounted to pedalling with only one leg at a time, revealed that the left crank’s readings were slightly high while the right crank’s were slightly low. On average, the combined number was reliable. We think the problem could be that Shimano calibrates the right crank without the chainrings installed and the strain gauges are tweaked when the rings are eventually bolted into place.
Temperature compensation isn’t good either – rises and drops can cause the R9100-P to drift by a few watts. On a long ride that began cold and later warmed up, the Shimano device tracked in line with the two other meters in the morning, but after leaving the bike in the sun for 30 minutes, the R9100-P’S readings were a few watts lower than the other two and remained so for the rest of the ride.
The Shimano device offers no indication of where you’re producing the power in each pedal stroke. Shimano has this capability with its Bikefitting. com hardware and software, but on its own the R9100-P only measures left and right wattage, and does so with that steady imbalance.
This meter will be specced on some 2018 bikes as standard, including the Giant Propel SL Disc, and you can expect reliable total wattage data plus Shimano’s great crank performance.