Garmin Rally RK200 Dual-sensing Power Meter pedals

The Garmin Rally RK200 Dual-sensing Power Meter pedals perform incredibly well, providing reliable and consistent power readings while also proving to be weather resistant, so far. What's really appealing is the ability to transfer its power-reading spindle from road to off-road pedals, for accurate data across disciplines.

The price is very high, but I'd say the Rally is worth it if you mix up your terrain across seasons or for the odd event, and are looking for SPD-SL (road) as well as SPD (off-road) cleat compatibility. But don't expect to change between the two every other ride – it doesn't seem that well suited for serious multi-discipline riders tearing it up on both tarmac and gravel each week.

> Find your nearest dealer here

Power meters use strain gauges to measure the force you're putting down and are most commonly placed in one or both pedals, one or both cranks, in the chainring spider, or in the rear hub.

Pedal power meters arguably have the best versatility as you can easily swap the pedals between bikes. Garmin's latest arrival builds on this concept, expanding the pedals' potential usage to include off-road terrain. The power meter itself being built into the spindle means pedal bodies are interchangeable, too; all you need to do is get the upgrade kit and teach yourself how to make the swap.

Are you a roadie? Well you are reading road.cc so let's go with yes. And did you recently invest in a gravel bike? A lot of us have, and so having a power meter that can be used across your road and gravel bike is the sort of versatility that would be of great help.

Not going to lie, since finding my way onto gravel tracks, I've half enjoyed these outings as a switch-off from the fields of data that I pace my road rides by. You're out in the middle of the countryside, away from cars and away from all that power data noise too, and it's just bliss – well, most of the time.

> How to go bikepacking: A beginner’s guide

Gravel terrain is also tough, requiring me to push with all my might to get up some steep ascents, so I've also been intrigued about my power numbers. While heart rate is a useful metric for gauging how hard you're finding the terrain, there's no denying that it's satisfising knowing how much you're truly trashing the pedals. This is where the Rally family can really help you out...

Rally family

The Rally power meter pedal system is Garmin's fourth generation power meter pedal, taking over from the Vector 3, with the original being the Vector pedals launched way back in 2013.

The new Rally range consists of Shimano SPD-SL (road), Look Keo (road) and Shimano SPD (off-road) cleat-compatible pedal bodies, with the option of either single or dual power measurement.

The model I have on test is the Rally RK200, which is the dual-reading road option for Look Keo cleats. Breaking that down, RK stands for the road with Look Keo cleats, while RS is for road with three-bolt SPD-SL cleats, and XC for two-bolt SPD cleats typically used off-road. Numbers-wise, 100 means single sided and 200 is for double-sided power.

You can start off with a single-sided Rally power meter, and later upgrade to dual power if left/right metrics become important to you.

As I've mentioned, the pedal bodies are also interchangeable with a conversion kit, as it's the spindle that's responsible for the power measurements. The Rally pedal ecosystem allows you to switch between Look and SPD-SL cleats, and even to completely different terrain with the off-road SPD system – there's a lot of scope for upgrading and adjusting if your needs change, or you've saved up some more money.

The RS and RK road pedals have a stack height of 12.2mm while the XC off-road pedals have a stack height of 13.5mm.

Garmin lists the Q-factor for all three options as 53mm, or 55mm with the supplied washers. Standard Shimano Dura-Ace PD-R9100 and Ultegra PD-R8000 pedals are 52mm, with the option to swap in a longer 4mm spindle should you want a wider stance. With just a 1mm-wider Q-factor, the Rallys can pretty closely match your current setup.

(Q-factor is a term for both the distance between the outer surfaces of the cranks, and the measurement between the centreline of the pedal and the end of the threaded section, as here.)

Set up and calibration

The Rally power meter pedals can be installed and removed with a standard 15mm pedal spanner, which means they are easy to move across bikes.

To connect up, the pedals can be paired with your cycle computer and the Garmin Connect app, as well as training platforms such as Zwift. The Rallys broadcast over ANT+, or Bluetooth for use with a greater range of electronic devices. If you have a device that is ANT+ compatible, make sure to pair with ANT+ as you're less likely to experience dropouts.

> 12 reasons why you should buy, and use, a power meter

Next up is performing a zero-offset (or 'calibration' as the Garmin Connect app calls it) to obtain accurate data, and this can be done easily from the Connect app or your cycle computer. If your crank length is not 172.5mm, make sure to change this field to the correct crank length before calibrating.

Garmin recommends performing this zero offset calibration once the bike is fully adjusted to the temperature it's in for the most accurate results – Garmin reckons that takes about 10 minutes per 10°C. So if you're doing a road ride, pop your bike outside before putting on your shoes, helmet, filling up your water bottle and so on, then 'calibrate' and off you go. Garmin's temperature compensation should then ensure that offset is maintained throughout if the temperature changes across the ride.

So much data

While the single-sensing pedals provide power only, the dual-sensing pedals offer you even more data for advanced performance insights, which Garmin calls Cycling Dynamics.

There's data on left/right balance, power phase (which part of the pedal rotation you're putting the power in), platform centre offset (whether you're pressing more on one side of the pedal platform), as well as seated and standing time.

It's an impressive analysis tool for sure, but I think Garmin's Cycling Dynamics seems more useful if recovering from injury – I don't really find myself analysing these metrics on a regular basis. However, the data is there, and so if you find yourself looking for minor adjustments to maximise your performance, you've got plenty to go by.

Battery

The pedals are powered by a single replaceable, disposable CR1/3N coin cell battery in each pedal rather than a permanent rechargeable system via USB, as used in Favero's Assioma Duos. If you don't have any CR1/3N batteries to hand, four LR44/SR44 batteries (two in each pedal) can be used instead.

Garmin claims that the Rally pedals have a battery life of 120 hours, which is significantly more than the 50 hours of the Assiomas.

To put the Rally battery life into perspective, on average I tend to ride no more than 10 hours a week, so that's 12 weeks of riding, three months, before needing to replace the batteries.

What's handy about the Rally cell battery system is that you can replace drained batteries with fresh fully charged up new ones instantly, so you're ready to record power again without any delay. You also aren't reliant on a mains socket or a portable battery pack, which makes things more straightforward and easier for bikepacking trips.

On the other hand, if you're a fair way through a battery, you can end up swapping in fresh ones before you really need to, just to be sure it won't run out – which is a little wasteful. With a rechargeable system you can just top things up. Also, it's easier to clip on the magnetic rechargeable cable than mess around with Allen keys and fiddly little batteries.

The removable battery covers (on the outer end of the spindle) could be a weak point for water ingress, and when changing the batteries these doors are also subject to wear and tear. The battery door can be opened with a 4mm Allen key, so not much chance of stripping the socket, unlike with 2mm bolts. Just in case they do get damaged, Garmin has made spare battery doors available for £25.99 (each side).

The battery compartment now has a metal thread and the battery contacts have been redesigned, as these were both problem areas for some Vector users.

Garmin gives an IPX7 water resistance rating, which means the pedals can be submerged up to 1 metre in water for 30 minutes and be all okay. Across the testing period I've ridden in heavy downpours and not had unusual data readings since – it appears to me that any issues with water damage have been solved with this new metal thread design.

Converting

Garmin hasn't sent me another pedal body to test transferring the spindle to, but I have attempted removing and replacing the spindle myself to understand the process, and to see how often I would be willing to make the swap over.

This is what you'll need to make the swap:

* 15mm pedal wrench

* Small Phillips screwdriver (PH 00)

* 12mm socket wrench with an outer diameter less than 17mm

* Torque wrench with 12mm socket head (to tighten the spindle nut to 10Nm)

* Bike grease

* 4mm Allen key

You can follow Garmin's video showing how it's done, or there are some read-through instructions here.

There are lots of tools to locate and the process is a little fiddly, but as with anything, you should get quicker the more you do it, especially when you aren't having to stop/start the video as you go along. On my second attempt it took me 15 minutes to remove and replace on the same pedal body (as I didn't have an XC one to swap to) for both pedals.

With the tiny 4mm screws I'd definitely want a table nearby to ensure I didn't lose them.

It's not something like switching between your racing wheelset and your hardier training wheels following your weekend's competitions or just before an evening spin in the lanes.

During the road racing season, I tend to ride four days a week on my road bike and one day on my gravel bike. So in theory I could do the switch on a weekly basis, but I'd be more inclined to only do so on a seasonal rotation or just before an off-road event, race or a self-organised multi-day bikepacking adventure.

Accuracy

Garmin claims the Rally power meter pedals are accurate to within +/- 1 per cent to the unit itself. If you're putting out 300 watts, the readings should always be between 297 and 303 watts. This is enough accuracy for keeping in the intended training zone for riding at the right intensity to get the benefits you're after for that workout.

As the accuracy percentage is to itself and not intended to be in relation to power meters from other brands, you may be wondering what's the point in comparing the numbers. Well, if you are going between power meters it can be useful to know how the power meter compares at both lower end and higher outputs. It's also handy knowing how fast the power meter responds.

I did a workout with a range of efforts from 5 seconds up to 10 minutes to spot any trends, comparing the data from the Rally pedals and my benchmark power meters after calibrating each device: an Elite Direto smart turbo trainer (+/- 2%) and Quarq DZero power meter (+/- 1.5%) that came as part of the SRAM Red eTap AXS groupset on the Liv Langma Advanced SL Disc I'm also currently testing.

Data analysis

You can find the full workout file with the power readings for each of the three power meter systems plotted together on a graph on Zwift Power over here.

For the 10-minute tempo effort you would have expected that the pedals would read the highest, and then the cranks and then the turbo, considering the losses and inefficiencies as you go from where your legs are exerting the power to the end of that chain.

Instead, the Elite turbo read highest at 208W, followed by the Rally pedals at 201W and the Quarq crank at 198W. Between the turbo trainer and the crankset, that gap is a little larger than what the +/-1.5% to 2% accuracy would account for, but hearteningly for the Garmin, it is at least within that for both those two power readings.

Make of the crank and turbo what you will, but the Rally pedals at least look to be in the right ballpark – it's not the outlier in any case.

Going up to ~300 watts for the 1-minute interval, we get a similar story, with the Elite turbo reading highest (311W average), Rally pedals in the middle (305W average) and Quarq crank the lowest (299W average).

In the sprints aiming for 700 watts, for maximum power value the Elite turbo is still reading highest (722W average) and the Rally pedals is in the middle (710W average) with the Quarq crank the lowest (696W average).

Overall, the percentage differences between the Quarq crank and Elite turbo from the Rally pedals stick between -1.5% and +3.5% across the 10-second and 10-minute tests. This shows that the Rally pedals are reading pretty consistently, relative to the other power meters, across lower and higher power values.

Looking closely at the shape of the graph for the 10-second sprints, the Quarq profile has a much smoother line compared to the Rallys, which is starting to get a little blocky, although not to the extent of the Elite turbo's line. The crank does seem to give a more complete picture of the data, but the Rallys do a good enough job at picking up the data for most needs.

Where the Rallys really impress is with how responsive they are to picking up when you start and stop pedalling. In the test where I pedalled for 10 seconds and stopped completely for five seconds, it was showing zero watts for four and five seconds, whereas the Quarq would only read zero for between one and two seconds, and the Elite didn't drop to zero at all.

Speaking from Zwift racing experience, to get into the super aero tuck position (so you can sneak in some recovery mid-race) a quick response time is important as the position is only activated when your power drops to 10 watts or less when you're travelling above 35mph (57km/h) on a 3% or steeper descent – the Rallys will cover you excellently for this.

Value

The single-sensing Rally pedals cost from £569.99 to £619.99, while the dual-sensing pedals cost from £969.99 to £1,059.99. Upgrading from a single-sensing system to a double-sensing system will cost an extra £489.99 to £529.99.

The dual sided Vector 3 pedals cost £849.99 so Garmin has upped the price with the Rallys. This price rise also increases the gap between Garmin's offering and that of Favero, the Italian competitor.

> Cycling power meters: explore these 25 systems to find the best one for you

Favero's Assioma Duo power meter pedals are a much more reasonable £699 for the dual-sided version, and £449 for the single-sided Assioma Uno version.

Weighing in at 300g, the Assioma Duos are also lighter than the Rally pedals I had on test, which tip the scales at 330g.

Previously, Favero's Assioma could only be used with Look Keo style cleats, but the new DUO-Shi is a spindle designed to fit into existing Shimano pedal bodies. There's a catch, though: Favero had to significantly increase the stance width from the industry standard 54mm to 65mm, which could lead to bike fitting issues for some riders.

Overall

Overall, the Garmin Rallys really impressed, but at that sky-high price you'd expect nothing less. Data accuracy is consistent and reliable for training and racing use, as well as measuring your efforts across different terrain. I've also been caught up in some heavy summer downpours during the test period, and haven't noticed any unusual readings since – with the new metal thread for the battery door closure, the Rallys appear to be much more reliable after rainy rides than the previous Vector 3 generation.

For multi-discipline riders, the Rally pedals are certainly an appealing system and this USP could justify the high price.

Just one caveat, though: riding off-road tends to be a more vicious experience, with pedal strikes being more common. I've only tested the road versions, and while there is that off-road compatibility, I cannot comment on its ability to survive these sorts of less avoidable knocks.

Verdict

Reliable and consistent data with useful swappable pedal body for different road and off-road cleats