First Look: Shimano Dura-Ace R9100-P power meter

After a long wait, Shimano’s Dura-Ace R9100-P crank-based power meter is now at road.cc for review and stock is beginning to arrive in the UK. Before we take it out on the road, here’s what we know so far.

The complete chainset (cranks, including axle, chainrings and integrated power meter) has an RRP of £1,499.99 (although you can find it cheaper). That compares to £499.99 for a standard (non-power meter) Shimano Dura-Ace R9100 chainset. 

You can also choose from a few bikes with the Shimano Dura-Ace R9100-P power meter already fitted, such as Giant’s Propel Advanced SL 0 Disc (£8,999).

Check out our guide to power meters here.

The power meter is visible when fitted but it’s hardly noticeable, the only tell-tale signs of its presence being small rectangular sensors – where the strain gauges are housed – added to the inner face of each crank. The non-driveside sensor extends inwards about 8mm while the driveside sensor doesn’t extend beyond the inner chainring so there’s no issue with clearance there.

There’s also a  transmitter that features an on/off switch which sits between two arms of the spider. Again, this is small and not particularly obvious unless you go looking for it. Oh, and there’s a little cadence magnet stuck to the driveside chainstay.

The strain gauges on either side of the chainset measure independently so you can get data on each of your legs – you can see the balance between them, for instance. You can also get smoothness and efficiency measurements but that’s the limit of the pedal stroke analysis – for now, at least. 

The separate parts of the system are joined together by an ‘LR connector’ that lives in the axle along with a rechargeable, non-replaceable battery – just one battery for both sides.

The Shimano Dura-Ace R9100-P power meter sends its signal via ANT+ so you can display it on a Garmin Edge bike computer, for example. Firmware updates can be sent wirelessly. It pairs with Shimano’s E-Tube app via Bluetooth.

Shimano said during the development phase that, “The built-in battery is recharged by a small magnetic adapter, so there is no cover to open,” but that has been changed somewhere along the line.

You recharge via the transmitter, the top flipping down to reveal a magnetic charge point for the USB cable. This looks the least robust part of the system because the hinges are tiny. That said, Shimano claims that a charge lasts up to 300 hours so it’ll rarely be open. 

The pods containing the strain gauges are sealed on to the crank arms – they can’t be opened. Shimano says that this design means that the system is completely waterproof although it doesn't give an IP rating. We’ll soon find out!

Shimano claims an accuracy level of 2%, which is similar to most other brands (their claims vary slightly but are usually 1.5-2%).

The Shimano Dura-Ace R9100-P power meter adds about 70g over a non-power meter chainset. You still get all of the other Dura-Ace chainset features: HollowTech II cold forged hollow crank arms, a hollow outer chainring to reduce flex and a four arm spider design.

We’ll be using Shimano’s power meter alongside those of other brands to compare the results. We use a PowerTap hub as our main point of reference, although you can’t get left/right there so we’ll need to add some power meter pedals to the mix.

We’ll be back with a review on road.cc soon.