Rally 100 and 200 are the previous generation of Garmin's pedal-based power meters, still sold alongside the 110/210 line. The measuring principle is the same — power is read at the spindle, so the meter travels with the pedals rather than living in one bike's crank.
Rally 100 is single-sensing, reading the left pedal and doubling it. Rally 200 is dual-sensing, giving true left/right balance and Garmin's cycling dynamics metrics. RK versions take Look KeO road cleats; XC versions take SHIMANO SPD cleats for gravel and mountain use.
The practical difference from the newer 110/210 range is the power source: these run on replaceable coin cells — two CR1/3N or four LR44/SR44 — for up to 120 hours, rather than a rechargeable pack. For riders who would rather carry a spare battery than a cable, that is an argument in their favour. Accuracy is within 1%, the rating is IPX7, and communication is ANT+ and Bluetooth.
