Stages Power LR - Shimano XT M8100/8120 Gen3

The Stages Power LR XT M8120 comes as a complete crankset including spider and chainrings and offers a dual-sided measurement on both crank arms. 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 crankset is increased by only 35 grams.

For mounting the Stages Power LR XT M8120 you need the TL-FC16 tool.

Dual-sided measurement

With the Stages Power LR XT M8120 both crank arms are equipped with measurement electronics. Thus, power and force distribution can be measured individually for each leg. Especially in case of muscular imbalances, dual-sided systems provide an advantage. This makes the Stages Power LR XT M8120 particularly suitable for ambitious riders who want exact power readings. For beginners and riders with on tight budget who can live without the last few percentages of accuracy, the single-sided Stages Power L XT M8100 is a good alternative.

Single-sided use

The power measurement takes place on both crank arms of the LR model. You can also decouple the two powermeters and use them individually on two different bikes. You get two power meters for the price of one.

Compatible bikes and groups

The Stages Power LR XT M8120 is compatible with Shimano XT M8120 and M8100 MTB groups. If a Shimano crank is already installed on your bike, you can simply replace it with the Stages LR crank. If a crank from another manufacturer is installed, the bottom bracket probably has to be replaced as well.
The left 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:

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 Stages power meter are well protected in a flat composite housing. 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 crank arms, the crank arms are 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 LR XT M8120 Powermeter is powered by two standard CR2032 button cells. The batteries are sufficient for about 175 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 two powermeters have a low weight of just 35g (15g left and 20g right). The powermeters are firmly connected to the crank arms. The weight is therefore to be understood as additional weight to the crankset.

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 LR XT M8120 Powermeter is very simple. The existing crankset 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 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.