Stages Power L - Shimano GRX RX810 Gen3

The Stages Power L Shimano GRX RX810 power meter is a single-sided power meter for cranks of the Shimano GRX RX810 series which is very popular with gravel bikes. It measures the power on the left crank arm. The Stages power meter is now available in the 3rd generation. It is positioned discretely on the inner side of the left crank arm, weighing in at a mere 15g.

It's accurate (±1.5%) and easy to install. Stages L power meters always come mounted to the left crank arm. So all you have to do is find the model which is compatible with your existing crank set and simply swap the left crank arm.

For GRX RX810 riders Stages offers a power meter as a replacement non-drive crank arm for existing GRX model cranks. Riders looking to add power to their existing crank need only select length, as the Stages Power meter for GRX fits all GRX cranks.

For mounting the Stages Power L GRX you need the TL-FC16 tool.

Single-sided measurement

With the Stages Power L, only the left crank arm is equipped with measurement electronics. The power is doubled to estimate the total power. Staying in your training zones or pacing a long climb or a triathlon usually works very well with a single-sided power meter. It becomes more difficult when one leg is significantly stronger than the other. Then the total power deviates. The Stages Power L is therefore particularly suitable for riders who can do without the few last percent of accuracy.

Compatible bikes and cranks

The power meter is mounted on the inside of the crank arm. Therefore, 10mm space is required between the crank arm and frame. With direct-mount brakes it is often too tight. You can check with a 10mm allen wrench whether a Stages power meter fits onto your bike. In the power meter area, the 10mm allen wrench must fit between the frame and crank arm:

The special thing about Shimano: the Stages Shimano GRX RX810 power meter fits not only to cranks of the same series, but to all Hollowtech II road cranks (eg 105 R7000 or Ultegra R8000). However, the Q-Factor is slightly larger on the GRX RX810 series. This means that the pedals are 2.5mm further away from the frame. So if the Stages Shimano GRX RX810 Powermeter is used with a road crank from the 105 or Ultegra series, then the left pedal is 2.5mm further out than the right pedal. This difference is quite small and most riders wouldn't notice the difference. In addition, you can move the cleat on the shoe a little.
Therefore, since Shimano gear is most often found on road bikes, the Stages GRX RX810 power meter is ideal for bringing it along to a training camp - provided that the rental bike also has a Hollowtech II road crankset.

Compatible bike computers and smartphones

Thanks to ANT + and Bluetooth Smart, the Stages power meter is compatible with all ANT + enabled bike computers and smartphones with Bluetooth Smart technology. With the 3rd generation transmission strength was increased by factor 6. Even triathlon watches, which were problematic with previous versions, now work seamlessly with the Stages power meter.

Construction and design

The left-sided Stages power meter sits well protected in a flat composite housing on the inside of the left crank arm. Strain gauges detect the slightest deformation of the crank arm due to the force applied to the pedal by the rider. Acceleration sensors are used to determine the cadence. This design makes it both discreet and well protected. Since the Stages power meter is firmly connected to the left crank arm, the crank arm is always included.

Tour tested

Stages has been very involved in professional cycling in recent years. The Stages power meter were thus represented in some Tour teams. In these extreme conditions for man and gear, the Stages power meter could prove itself.

Battery

The Stages Shimano GRX RX810 power meter is powered by a standard CR2032 button cell. A battery is sufficient for about 200 hours of operation time. The CR2032 is widely used and inexpensive. It is available at almost every supermarket. The battery can be changed without tools. The LED on the power meter provides information about the battery level.

Weight

The actually power meter has a low weight of just 15g. The power meter is firmly connected to the left crank arm. The weight is therefore to be understood as additional weight to the crank arm.

Accuracy

We were able to confirm the accuracy of +-1.5% several times on our calibrated Cyclus II ergometer in the laboratory and in comparison with other power meters on the road. The measurement accuracy must be put into perspective somewhat, since the measurement is only one-sided.

Cadence

The cadence is determined by means of an accelerometer and an integrated ring laser and transmitted to the bike computer or smartphone. An additional cadence sensor is no longer necessary. Measuring cadence via acceleration sensors has long been a major challenge for engineers. In the 3rd generation of the Stages power meter, it now works perfectly.

Temperature compensation

When temperatures change, different materials expand differently. This can have a significant impact on the measurement accuracy of a power meter, as the strain gauges react to even the smallest changes. The Stages power meter therefore has active temperature compensation (ATC). This means that it delivers precise measurements even when temperatures change.

Calibration

Each individual Stages power meter is individually calibrated at the factory. Something else is the zero calibration (also called "Zero Offset" or "Manual Zero"), which should be done before every ride. This is similar to a scale that also "zeros" itself before weighing. For zero calibration, the Stages power meter must be active and connected to the bike computer or smartphone. The left crank arm must now point straight down. Now the zero calibration can be performed on the bike computer or smartphone.

Oval chainrings

The measurements of the Stages power meter are distorted by oval chainrings and are usually 4-5% higher than with round chainrings. The more oval the chainrings are, the greater the influence on the power readings.

Setup / Firmware Updates

Unlike other power meters, the Stages power meter does not need to be specially set up or registered. The correct crank length is already stored in the power meter. Firmware updates require the Stages App (Android & IOS) and a smartphone. We recommend always using the latest firmware of the power meter and the cycling computer.

Installation

The installation of the Stages power meter is very simple. The left crank arm of your crank is simply replaced by the Stages crank arm. For the Stages Shimano GRX RX810 power meter you need a 5mm allen wrench and the Shimano TL-FC16 crank assembly tool. It's needed to loosen or tighten the bolt that pulls the left crank onto the axle.

Durability

We have made good experiences with the durability of the Stages power meter. Due to its placement on the inside of the left crank, the power meter is well protected against mechanical influences. In a crash, for example, a pedal power meter usually gets somewhat beaten up. This is where the Stages can score. The first generation had problems with the housings. The use of an unsuitable composite led to cracks forming in the housing and water being able to get inside. However, these problems have been completely resolved with the 3rd generation. However, it still happens occasionally that water gets inside. This is usually due to an improperly closed battery cover or an improperly fitted sealing ring. When replacing the battery, please make sure that the sealing ring is correctly seated and that the battery lid is fully locked.

Warranty and support

The Stages power meter comes with a 2 year warranty. The Stages power meters are manufactured in the USA in Boulder, Colorado. However, Stages also has a base in Germany, which is responsible for sales and support in Europe. The support is very good and extremely customer friendly. If there is ever a problem, we have a direct line to Stages Europe and can help you quickly.