Stages Power R - Shimano XT M8100/8120 Gen3

The Stages Power R XT M8100 is a right-sided power meter and comes with spider and chainring but without left crank arm. The Stages Powermeter is now available in the 3rd generation. The Gen3 models have a more accurate measurement, stronger transmission power to the bike computer and an improved cadence sensor. The total weight of the crank is increased by only 20 grams.

With the Stages Power R, you can upgrade an existing Power L powermeter to a dual-sided system. 

For mounting the Stages Power R XT M8100 you need the TL-FC16 tool.

Single-sided measurement

With the Stages Power R, only the right 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 R is therefore particularly suitable for riders who can do without the few last percent of accuracy.

Upgrade for the Stages Power L

With the Stages Power R XT M8100 you can upgrade your existing left-sided Stages Power L power meter to a double-sided system. Simply pair the two devices in the Stages app.

Compatible bikes and groups

The Stages Power R XT M8100 is compatible with Shimano XT M8100 MTB cranks. If a Shimano crank is already installed on your bike, you can simply replace it with the Stages R crank. If a crank from another manufacturer is installed, the bottom bracket probably has to be replaced as well.

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 right-sided Stages power meter sits well protected in a flat composite housing on the inside of the right 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 right 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 Power R XT M8100 Powermeter is powered by a standard CR2032 button cell. The battery is sufficient for about 200 hours of operation of the powermeter. 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 20g. The power meter is firmly connected to the right 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 assembly of the Stages Power R XT M8100 Powermeter is very simple. The existing right crank arm is simply replaced by the Stages crankset. For Shimano cranks, this requires only a standard 5mm allen key and the  TL-FC16 tool. With a little practice, the installation is done within 5 minutes.

Durability

We have made good experiences with the durability of the Stages power meter. Due to its placement on the inside of the right 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.