Garmin Rally RS210 Review: The Rechargeable Rally

Pedal power meters occupy a specific place in a pain cave. Your trainer already measures power, so a second measuring device looks redundant until you notice what it actually does: it is the only number in your setup that follows you outdoors, onto a second bike, and into a race, which makes it the reference everything else is checked against. That is the job Garmin's Rally range has always done, and the 210 series is the first redesign of it in years.

The change is not the sensor. It is the spindle. Garmin has replaced the replaceable coin cells and their threaded battery doors with a sealed, internally rechargeable lithium-ion spindle, charged through a magnetic clip, and quotes up to 90 hours of ride time between charges with a 15-minute quick charge worth about 12 hours. Along with it comes Pedal IQ, a calibration assistant that tells you when a manual calibration is genuinely needed, and a universal spindle that moves between road and off-road pedal bodies.

What actually changed from the 200 series

Three things, and only one of them is visible on a spec sheet.

The battery is now sealed and rechargeable. The Rally 200 and the Vector pedals before it used replaceable cells behind a threaded door with a seal, and that door was the single most complained-about part of the design: cross-threading, seal wear, water finding its way past it. The 210 spindle is closed. You charge it with a magnetic clip on a USB-C cable, which road.cc found straightforward in testing. That is a durability fix, not a performance one, and it is the reason to care about this generation.

The spindle is universal.Rally was always convertible in principle — the electronics live in the axle, so a body kit changes the cleat system — but the 210 series standardizes one spindle across the RS, RK and XC bodies. Swapping bodies or moving the meter to another bike is a 15 mm pedal wrench and a hex key.

Pedal IQ arrived.Garmin's calibration assistant watches temperature change, time since the last calibration and whether the pedals have been moved between bikes, then tells you when a manual calibration is worth doing. Every power meter needs the occasional zero offset and almost nobody remembers — our calibration guide exists because of exactly that. The caveat is that the alerts want a recent Garmin Edge, so part of the feature is locked to the ecosystem.

What did not change: the ±1% accuracy claim, dual sensing on the 210, single sensing on the 110, ANT+ and Bluetooth broadcasting, and the cycling-dynamics metrics on a compatible head unit.

Why a pedal meter matters to an indoor rider

A smart trainer measures power at the flywheel, after the chain, the cassette and whatever the drivetrain is losing that day. A pedal meter measures at the point where you apply force. The two will never agree exactly, and they are not supposed to — the difference is drivetrain loss, usually a couple of percent. road.cc saw exactly that pattern testing the RS210 against a Quarq crank meter and a Kickr Core, with the pedals reading slightly higher.

What the pedal buys you is a stable reference. If your trainer drifts, you will see it. If your FTP was set outdoors and your indoor sessions feel wrong, you can find out which device is lying. And when you replace the trainer, your training history stays comparable because the measuring device did not change. That case is set out in full in smart trainer vs power meter, and how accurate are smart trainers explains why the numbers differ even when both devices are working correctly.

Ninety hours, and the routine that comes with it

This is the honest cost of the redesign. The Rally 200 ran roughly 120 hours on cells you replaced when they died; the 210 states up to 90 hours and then needs a cable. For most riders that is several months of training, and the 15-minute quick charge covers the moment you notice a low battery the night before a long ride.

Two practical notes, both from Garmin's own documentation. The pedals are rated IPX7 and will operate from -10 to 50 degrees C, but the charging window is narrower at 15 to 40 degrees C — if the bike lives in an unheated garage in winter, bring the pedals inside to charge. And the magnetic charging clips are small, proprietary and easy to mislay, which is the sort of thing that only becomes irritating in year three.

Dual-sensing or single: the 210 or the 110?

The 210 measures both legs independently. The 110 measures the left and doubles it, with a dummy right pedal. Both claim ±1%, because that figure describes how well each pedal measures what it can see, not whether doubling one leg reflects your body.

For tracking fitness, the 110 is enough. Training adaptation follows repeatability, and your left-right split is normally stable enough that a doubled number moves with the real one. The 210 earns its premium in three specific cases: rehabilitation after a one-sided injury, where watching asymmetry close is the point; riders with a known and large imbalance; and anyone whose coach or bike fitter genuinely uses the balance and cycling-dynamics data. Outside those three, it is a metric you will admire once and never act on — the same conclusion our single vs dual-sided power meters guide reaches for the category as a whole.

Which pedal body: RS, RK or XC

The 210 spindle ships in three bodies. RS takes Shimano SPD-SL road cleats, RK takes Look Keo, and XC is the two-bolt Shimano SPD mountain-bike pedal. Choose the one matching the cleats already on your shoes; there is no performance difference between them and the road versions cost the same.

For an indoor setup specifically, the XC deserves a mention. Two-bolt SPD cleats are recessed into the sole, so the shoes walk normally — which matters more than it sounds when the pain cave is at the other end of the house and you are carrying a bottle. The XC bodies are all metal and heavier at a published 436 g the pair against 312 g for the road versions, but indoors that weight is irrelevant. And because the spindle is universal, this is a choice you can reverse with a body kit rather than a new power meter.

Rally RS210 versus Favero Assioma

This is the comparison that decides most purchases, and it is not close on price. Favero's dual-sensing pedals claim the same ±1% for substantially less money, and road.cc — which scored the RS210 7 out of 10 — named price as the single reason, noting the Garmin costs a large premium over Favero's equivalent with no obvious advantage in the data. The Favero is also lighter: road.cc puts the RS210 at 312 g the pair against 247 g for the Assioma Pro RS-2.

Garmin's answer is the parts of ownership that are not the watt. Convertible bodies, so one meter serves a road bike and a gravel bike. Pedal IQ, so calibration stops being a thing you forget. Native cycling dynamics on an Edge. And now a sealed spindle that removes the failure point owners of previous Garmin pedals will remember. If none of that is worth a premium to you, buy the Favero — that is the buyer-first answer, and our Assioma vs Rally comparison goes through it in detail.

Should you upgrade from a Rally RS200?

No, not on the data. The accuracy claim is identical, dual sensing is identical, and the metrics on your head unit are the same. Nothing about your training gets better.

Upgrade only if the battery door has become a problem — if you have had water ingress, a stripped thread, or a pedal that keeps dropping out and a new seal has not fixed it. That is a real and common failure and the 210 is the fix for it. If your RS200 is working, keep riding it and spend the money on something that changes your training instead — a proper fan does more for an indoor rider than any second power meter ever will.

Who should buy it

Buy the RS210 if you own more than one bike, or one bike and a plan to buy another, because moving the meter takes two tools and no decisions. Buy it if you might change cleat systems, because it is the only power meter where that costs a body kit and not a replacement. Buy it if you have owned Garmin pedals before and the battery door is the reason you are shopping. And buy it if a Garmin Edge is the center of your setup, where the cycling dynamics and Pedal IQ alerts actually surface.

Skip it if you want the cheapest trustworthy watt — that is the Favero Assioma Duo, or the Rally RS110 if you want to stay in the Garmin ecosystem. Skip it if you ride one bike, in one pedal system, forever, because you are paying a premium for flexibility you will never use. And skip it entirely if you do not yet own a smart trainer: indoors, the trainer measures power on its own, and a pedal meter is the second purchase, not the first.