A single-sided pedal-based power meter for road cycling can deliver accurate and reliable power measurement at a great price. If straightforward power information is what you need to develop as a cyclist, the Garmin Rally 100 series pedals are a great choice. For road pedal/cleat bodies, Garmin is offering two versions, one set-up for Look Keo cleat compatibility (RK100), and this RS100, which is for Shimano SPD-SL cleats. All other aspects and details are the same. Garmin previously offered the Vector series power meter pedal system, and the Rally-series are built from the development and hard-earned lessons from the Vector 3. The axle design of the Rally series, which carries the power measurement devices, communication gear and replaceable battery is a physical match for the final version of the Vector 3 design. It is true the Vector 3 had some issues, but these were generally related to the battery system. Garmin has worked through iterations to correct this, and by all accounts, the final Vector 3 solution has been effective. There was never a real issue with the accuracy of the Vector 3, so Garmin knew it had a proven measurement system. The battery itself, the battery port cover and seal, as well as the threaded receiver in the pedal body have all been fully updated in the Rally series.

One major selling point of the Rally is the fact that the axle system is universal to all Rally pedal bodies, both R and XC models, and is backwards compatible with the Vector 3. This allows the bodies to be interchangeable as all have the same bearing system as well. So if you have a Vector 3 and want to convert it an SPD mountain body, which offered as complete pedals or an upgrade body set, you can use the existing axle to make the change. Or, if you normally use road pedals most of the year, and mountain pedals in the winter, as many cyclists do, you could change out the bodies and have all the same power measuring benefits year round. This modular system offers this benefit, and potentially other options down the road, if you will.

The Rally RS100 pedals install like any pedal and have wrench flats for a standard pedal wrench. There is a torque spec recommended (34Nm), which is bit more than most pedals recommend, but torque won't impact the power measurement. Just make sure the pedals are tight. With the Rally 100 series pedals the power meter is in the left pedal. As it installs like any other standard pedal, it is easy to swap your RS100's from bike to bike. You are then free to measure power and cadence via the various metrics and processing done via your head unit. One note, as a single sided power meter, the Rally 100 pedals don't trigger Garmin's advanced Cycling Dynamics. Those require a dual sided system. Not everyone needs Cycling Dynamics, but if you start with the Rally 100 pedals and want to upgrade, you will have the ability to add the power meter version of the right pedal, sold as a standalone items. Just know that the in the dual set-up, the right pedal communicates with the left, and the left communicates with your computer head unit. As far as choosing SPD-SL versus the Keo version, if you already ride SPD-SL pedals/cleats it keeps things simple, Garmin does provide cleats, but the Shimano cleats are 100% compatible. Some cyclists prefer the slightly larger cleat platform of the Shimano system over the Look Keo, but many Keo riders feel just as strongly about that design. This comes down to preference and most likely what you use now.

As far as accuracy, the Rally RS100 has been tested at +/- 1%, which is the equal of the best power meters on the market. Garmin equips them with both ANT+ and Bluetooth communication so you have ease of set-up. Generally we recommend using ANT+ for stability and simplicity, especially with Garmin Edge GPS head units and compatible wearables, but you have options. Pairing is generally fast and simple. Generally you will performing field calibration regularly, and at release Garmin recommends allowing your bike to acclimate to outdoor temperatures for 10-15 minutes. This allows the temperature compensation to be more accurate. As mentioned, the Rally 100 pedals transmit power and cadence, with speed coming from GPS for most users, but you can always had a speed sensor to your bike if you prefer direct measurement. Battery life varies but is rated to 120 hours. It is easy to change the CR1/3N battery via the compartment cap on crankside end of the pedal axle. Garmin does have a weight limit on Rally pedals, at 231.5 lbs. The set-up is rated to the IPX7 level for water protection, which means it can stand submersion in 1 meter of water for 30 minutes, so the seals can easily handle even the rainiest days and wet roads.

Given the nature of today's stronger communication standards and compatibility across systems, the Rally 100's are very user friendly with Garmin/Tacx family equipment and apps, as well as third-party apps such as Strava, TrainingPeaks®, TrainerRoad and many more. Even if you don't race or plan to race, understanding your power output can improve you as rider by informing how you can improve or be more efficient, as well as helping you to understand when you need a rest or easy day to prevent overuse. If you are ready to undertake the challenge of improving, or are unhappy with a different power measuring option, the Garmin RS100 SPD-SL Pedals are an ideal way forward.