In just a few years, power meters have moved from being pro-only equipment to affordable training aids for amateur racers and keen recreational riders. When used properly, a power meter gives you potent information that can vastly improve your training and pacing.
Compared with a heart-rate monitor, a power meter delivers objective measurement of the work you’re doing, regardless of how your body feels about it. Heart rate, by contrast, is greatly influenced by fatigue, temperature, adrenaline and that caffeine gel you just sucked down. Heart rate also responds very slowly: do a short sprint with lots of power, and your heart rate will barely rise before you finish; coast over the top of a hill that you just hammered up, and your power drops to zero yet your heart rate continues soaring.
A power meter helps you to define your training zones and then train in them correctly. Power meters are also the perfect tool for pacing your effort, whether on a 10-mile time trial or a 100-mile sportive.
For this feature, we tested eight meters, including the two pedal-based systems from Garmin and PowerTap, the revised version of the Stages crank (the device that arguably kickstarted the affordable power meter market), the new Infocrank and INpower and the standard-setting SRM.
More than 80 rides went into this test, and for each one we ran three meters at once, with three identically configured Garmins on the bars to record the data. Using one meter on its own makes it impossible to tell if it’s accurate or not; two is better but you won’t know which is reading incorrectly if the shift is small. With three, you can see when one is out but the other two are in agreement. Of course, it’s possible that they could all be having a bad day but we’ve done our best to eliminate that by doing so many rides.
Things to consider when shopping for or using a power meter
- Strain gauges: You can’t see them but these thin strips of metal are bonded in place to a structural part of the meter. As force is applied to, say, the crank, it deforms by a microscopic amount and the strain gauges deform with it, allowing a calculation of force, and ultimately power.
- Compatibility: Power meters can be built into pedals, cranks and hubs, and your bike(s) may influence your choice. For instance, the Stages isn’t yet offered for Campagnolo; the Infocrank and Rotor only come with a 30mm spindle; both the Garmin and PowerTap pedal systems dictate that you use Look Keo cleats.
- Weight: The lightest of these systems adds just 20g to your bike; the heaviest nearly 300g. If weight really matters (ie, you have a sub-7kg bike, sub-7% body fat) then weight should be part of your decision, but otherwise we think it is secondary to performance, as with most things.
- Battery: Nearly every meter now has a user-replaceable battery, usually a coin type. You should travel with spares because Murphy’s Law dictates the battery will run out on day one of that big trip to a race or vacation.
- Manual Zero Offset: This is a simple pre-ride calibration check that most power meter companies say you should do. A few say it isn’t necessary but it’s still good practice. If you keep your bike indoors and it’s cold out you may also need to repeat the calibration 10 minutes into your ride.
The best power meters of 2016
Quarq Elsa RS
The Elsa RS is Quarq’s top-line model made for Shimano four-bolt chainrings. The 781g unit (with chain rings) looks the part, too, perfectly blending into a Dura-Ace drivetrain. Quarq has come a long way in a relatively short time, with constant updates and innovations since its launch back in 2008. Since being bought by SRAM in 2011, the pace of progress has only increased and we’ve seen a flurry of new features and price drops.
- Pros: Accuracy, consistency, simplicity, value
- Cons: No Bluetooth
The most significant of several recent developments by Quarq is the switch to accelerometers in place of a magnet for cadence. It makes installation much easier because you’re simply fitting another crankset. Pairing is easy anyway, and helped further by the thoughtful inclusion of an LED status light and the ANT+ ID on the outside.
Quarq meters measure power at the spider, like an SRM. It’s a good method as it means the expensive and fragile bits are tucked neatly away where they’re hard to damage. It does mean that left and right power can’t be measured independently but Quarq has beaten SRM to a trick by using crank position to calculate the effort from each leg. It’s just as good and always gave the same split as whichever power meter pedals we were running.
Another crucial feature is Quarq’s ‘10K’ temperature compensation algorithm. Older models were more vulnerable to temperature variation but this one has it covered. You should still do a pre-ride manual zero offset but after that the Elsa RS does it all.
Over hundreds of miles the Elsa RS never put a foot wrong. It responded quickly, tracked well with other meters, caught sprints well and never gave us any grief. In short, it’s brilliant.
- Read the full Quarq Elsa RS review: “Intense development has paid off. This is a great power meter and top value, too”
Stages Dura-Ace 9000
It’s because of Stages that we’re here doing this group test. Stages inadvertently kickstarted a price war with its headline-grabbing Stages 105 crank in 2013, which was nearly half the price of everything else on the market. Now there are many more affordable options. Stages gave power to the people.
- Pro: Lightest on test, simple, consistent, now tougher, good price
- Con: Limitations of left-only
When it launched, Stages was unique for being a left-side-only crank based meter. This design makes it more affordable, less complex and easier to fit. Power is measured with strain gauges factory-bonded to a left crank, doubled and then sent to a head unit via ANT+ to a computer or Bluetooth to a smartphone app. It’s also super-light: this one was just 20g more than a regular Dura-Ace crank, making it the lightest on test.
The limitation of a left-only system is that it can’t account for a difference in your left-right power balance and very few people are truly 50-50. What’s more, your balance isn’t consistent. A bit of muscle tightness in one side will skew your balance slightly, easily creating errors of as much as 6%. To non-power meter users that may not sound like much but to long-time users a 6% error in a time trial or interval session is a big deal. Add in a real injury and your data will be way out. That said, Team Sky uses Stages and have just renewed their deal.
Pairing, waking and pre-ride calibrating is all very easy, and once paired you don’t have to mess with it again as it uses an advanced temperature compensation method that prevents drift if your bike lives indoors or if the weather warms up after an early morning start.
We got good data that tracked very closely with other meters in simultaneous testing. It caught sprints well, too, which we didn’t expect from a lefty.
For the first two years or so of production the battery cover was a weak spot, leading to problems and earning Stages a reputation for being fragile. But this has now been beefed up, and having used both we can say it’s much more robust. While this Dura-Ace version faces stiffer competition, the 105 and Ultegra versions are still untouchable as affordable introductions to training with power.
- Read the full Stages review: “The much-improved Stages is a great first power meter and the 105 version is the best value”
The INpower is a fresh design approach. While other crank-based power-measuring systems position the strain gauges in the crank arms or the spider, Rotor’s meter houses the electronics in the crank axle. Like a Stages, the INpower only measures on the left side, then doubles that number for total wattage. But housing the guts in the axle brings benefits: the weight is centred; the unit is protected from water, dirt and impact; there’s room for a larger battery; and it allows a modular design that can be used with all of Rotor’s existing cranks, including the aerodynamic Flow model. It weighs 574g without chainrings.
- Pros: Light, robust, affordable, accurate
- Cons: Limitations of left-only design, doesn’t catch sprints well
Rotor offers the INpower as both a crankset and the left side on its own, so you can upgrade your existing Rotor crankset to INpower. There are other gains to usability too. The inexpensive and widely available AA battery lasts a claimed 300 hours, you can swap it yourself in seconds without tools, and the cranks are now easier to remove thanks to a captive bolt. You can pair your INpower with any ANT+ compatible device.
Rotor has also introduced its own software with new analysis tools for users of its own Q-Rings: Torque 360 and Optimum Chainring Angle. The first is a spin scan, the second guides your choice of Q-Ring mounting position. Of course, any such analysis is limited by only having view of one leg’s work, though Rotor will soon have a dual-sided 2INpower meter for sale.
We found the INpower to be a big step up on from the soon-to-be-discontinued Power LT. It doesn’t jump or drop out and it’s fine at low cadences; it tracked very well with our PowerTap GS control; and it handled temperature changes, though it did take a while to adjust. On the downside, like the Power LT, the INpower under-reads sprint efforts. It does this consistently, so the numbers aren’t useless, but if you’re a road racer or compete in criteriums you may want more precision.
SRM Power Meter
The SRM system is the granddaddy of power meters; it was already well established when PowerTap came along in 1998. By comparison, the likes of Garmin and Stages have been doing this for about five minutes. And it shows. SRM is still viewed as the gold standard and this unit didn’t disappoint. Only three units were completely faultless throughout testing, and this was one of them.
- Pros: Reliability, consistency, battery life, crank options
- Cons: Very expensive, no DIY battery swap, no analysis, requires frame magnet
But, if being the granddaddy sounds a bit like being a dinosaur, well that’s also true. SRM hasn’t gone out of its way to move with the times. This is the only meter that still requires a cadence magnet to be glued to the frame. It can’t do left/right split either, and you can’t replace the battery yourself, you have to send it away and do without it for at least a few days – though the battery can last years, and a rechargeable version is in development.
The most obvious downside is the price. SRM recently cut its prices across the board, but they are still the most expensive meters on the market.
There is no pedal stroke analysis and the new (and pricey!) Power Control 8 head unit lags about a decade behind a Garmin 1000, but the system is compatible with any computer that can receive ANT+.
SRM makes up ground is on consistency. Across our office we’ve done thousands of miles on this and two other SRM units with no data anomalies at all. A manual zero offset is necessary before you set off and then the SRM handles temperature variation superbly. You can be confident in the data, and that’s very important. The only caveat is that because the SRM uses a magnet for cadence, it’s more prone to over-reading slightly when used with non-round chainrings. Even Team Sky were fooled by that one for a time.
- Read the full review of the SRM: “A great power meter but rivals now match its performance, with more features and less cost”
Verve is the newest name to the power meter market and came in swinging, claiming the Infocrank is the most accurate meter available, with twice the fidelity of an SRM. It’s a true left/right system, with four strain gauges in each crank arm. A key difference is that these cranks were designed from the outset to be a power meter, so the strain gauges are placed in the precise load path to avoid data corruption by twisting forces. Verve claims its data is accurate to within 1% across the full measurement range of 0-3,000w, and says there’s zero temperature drift or need to perform a pre-ride manual calibration – and our tests back that up. This is a true get-on-and-go meter.
- Pros: Accuracy, consistency
- Cons: TA rings, chunky looks
The Infocrank comes with specific bottom bracket cups and has a 30mm axle so should fit most frames. Infocrank uses a magnet and reed switch for cadence but has a clever magnet bracket that clamps over the bottom bracket. Infocrank says a magnet prevents data corruption from poor road surfaces.
The 110BCD crankset comes with Praxis rings in 50/34 or 52/36, or TA Syrius rings in 53/39. Our test set came with the latter and we noticed a small decrease in shifting performance. The five-bolt pattern does mean you can use other chainrings.
There are two LR44 batteries on each side under a bolt-on cover. They’re readily available, quick to swap and are claimed to last 500 hours. Fans of marginal gains may sniff at the above-average 195g weight penalty over a Dura-Ace 9000 crankset, and even the aero implications of such broad and square cranks, though only high-level hill climbers and time triallists should give it a second thought.
When it comes to the crucial stuff, delivering clean and accurate data, the Infocrank excels. Throughout testing it was faultless. Verve suggested that it might read lower than other meters but we found it tracked alongside. We can’t say if it’s accurate to 0.5% or 1%, and for all Verve’s claims and unique design it didn’t do anything better than the SRM or Quarq, but they don’t leave much headroom anyway. The Infocrank is an excellent power meter.
- Read the full Verve Infocrank review: “Newcomer delivers excellent performance and runs the biggest names very close”
First launched in 2010, the German-made power2max beat Stages to market with an affordable meter, but didn’t have the same transformative impact. That was largely because power2max is only available to buy direct online (from Germany for Europe – there’s a separate US site), so the brand had no distributors helping with marketing.
- Pros: Excellent data, great value, Campag option
- Cons: No four-bolt Shimano version, awkward battery swap
But it’s also because it wasn’t quite competitive. While keenly priced, the early models didn’t fit all frames and chainrings, and struggled with temperature changes. This second generation Type-S addressed that two years later.
Temperature compensation is built in, the fit is near universal, it no longer requires a magnet on the frame and it’s better value than ever, with prices starting from €690 with modest but decent FSA Gossamer cranks and topping out at €1,590 for this smart new four-arm Campagnolo version with carbon cranks. Movistar uses power2max meters; they are no longer the outsiders. The range of other cranks on offer is good but there’s no four-bolt option for Shimano chainrings.
The other feature added for the Type-S is estimated left/right split. Like the Quarq, it’s calculated based on crank position rather than measured independently like the Verve. It never quite agreed with the Garmin pedals, though, and the Quarq did.
The data from the power2max is excellent. It handles the tougher tests of sprints and low cadence training easily, tracks consistently and handles temperature changes smoothly. P2M says a pre-ride zero isn’t needed, so like the Verve you can get on and go.
Garmin Vector 2
The Vector was the world’s first power meter pedal but it wasn’t perfect. For the revised version Garmin has added lots more analysis and changed the pods, which proved very robust. Transferring between bikes isn’t as quick as with the PowerTap P1s, but still takes only a few minutes. As well as having to mount the pods, you also need to torque the pedals correctly to 40Nm. That’s higher than normal and you can’t afford to get it wrong, as the Vectors will read incorrectly if not tightened to spec. Each pod takes a CR2032 battery.
- Pros: Transferability, light, robust, extra analysis
- Cons: Not the best consistency and accuracy, dictates Look cleats
The Vector 2 requires an ‘installation ride’ to teach the pods the precise angle they are set to in relation to the crank. This only takes about 30 seconds, then your computer asks you to confirm crank length and do a manual zero offset calibration.
The Vector 2 is also available in a single-sided Vector 2S as a more affordable entry point that can then be upgraded to a dual-sided system. You can also upgrade your original Vector pods to V2.
The new Cycling Dynamics features are interesting. Using a Garmin Edge 1000 you can see live displays of your left/right power, stroke efficiency (Power Phase) and seated/standing splits. Some of this is a bit gimmicky and only there because it’s possible, but the Power Phase feature is useful, especially if you’re a newer rider working to develop a smooth spin.
The Vector 2 performed well for lots of rides but also gave us a fair bit of grief. It’s sensitive to temperature and it also over-read sprint efforts of over 900W by as much as 30% compared to theother two meters when it had tracked alongside them for the rest of the ride.
Then the left pedal started reading low, before cutting out completely. Swapping the batteries and pods didn’t fix it. Garmin said it was a ‘firmware issue’ but replaced the whole set with new ones. It should also be said that Garmin’s warranty backup is very good, and for the rest of our testing the second set performed without any problems, so maybe Garmin is ironing out some bugs.
- Read the full Garmin Vector 2 review: “The best power meter pedals but not as refined and reliable as we expect”
Back when the only other choice was an SRM that required a mortgage, the early PowerTap hubs earned a big following because you could build a basic rear training wheel for a third of the price of the German cranks. That’s still the case now, though there are now many more affordable meters to rival it. But the basic problem persists with a hub-based system — it is literally bound to a particular wheel.
- Pros: Accurate, consistent, fits any bike
- Cons: Obvious limitations of wheel choice
As well as cheap training wheels, PowerTap offers complete race wheelsets including exotic Enve rims. We started this test with a G3 hub in a 45mm carbon clincher wheelset but it started reading low and then failed one day. We were told it was due a service after 100 hours of use, though the recommended interval is annual. We then switched to a GS hub (and re-did some test rides to check parity) in an Amp 35 carbon clincher wheelset. At 1,640g, they’re quite light for clinchers with a power hub and the modern, blunt profile gives good stability and speed, though it’s no Enve 3.4 and the heavier rear wheel is noticeable. Wet braking was good from new but faded badly and is now poor. The GS is the same power meter but built into a hub with DT Swiss mechanicals and straight-pull spoke arrangement. A disc brake version is also available.
The price is for the hub only.
The meter is easy to pair, wakes with a spin and calibrates quickly. Throughout our testing the second hub remained consistent, with no bad data and no hiccups at low cadence or in sprints. When the battery needed replacing after several months’ use, doing so was easy using the supplied tool to remove the ‘Powercap’ cover and swap the CR2032 cell. As the GS was the control meter and in the bike with every combination of meters, it had the toughest test and covered more miles so its consistent performance went some way to mitigating the problem with the earlier G3.
The obvious downside of a hub power meter is that you are constrained to that wheel or have to buy a second hub to build into a race wheel. If you need to use several wheelsets, or even think you’d like the option to upgrade, then one of the better-performing crank systems makes far more sense.
- Read the full PowerTap G3 review: “The PowerTap is a very good power meter that’s put in the shade by more practical rivals”
£999 / $1,199 / AU$1,799
The P1 pedals came to market with one big trump card – transferability. With no pods and no torque requirement the P1s are as easy to fit as any other pedals so are easy to swap between bikes. Unlike the Garmin V2, the P1s also fit every crank. There are some downsides, though, and the first is immediately apparent: the P1s are very chunky. At 429g for the pair, they add 200g compared to most good pedals and they reduce ground clearance. While that’s only of concern to racers, the fact that the edge of the battery cover is the first thing to hit should worry anyone. The first cornering scuff nearly ruined the pedal body; we were very careful after that.
- Pros: Easiest to transfer, value
- Cons: Weight, cornering clearance, some sketchy data, no left-only option
Pairing and initial set-up is very easy, and they wake up when you spin them or start riding. As pedals, they’re fine. The supplied Keo-style cleats give very loose float; with real Look Keo cleats they feel like other Look pedals, with clean engagement and release. Their weight means they always hang at the right angle to locate the cleat. The AAA batteries lasted just 80-100 hours, and we didn’t get a ‘low battery’ warning on our Garmin – you have to check for the green flashing light on the pedal to go red. Soon after that they won’t wake up, so keep spares handy and check or swap them before that big sportive you’ve been targeting.
Generally the P1s tracked very well with other meters and performed well. They handle both low cadence work and sprints without deviating. However, we had more bad data from the P1s than any other meter including half a dozen spikes of over 30,000 watts and repeated over-reading by 8-10% when above 300W during intervals and TTs. The latter is more troubling because it was only when using multiple meters that the error was apparent and at under 300W they tracked properly. PowerTap says both errors were a firmware glitch and that an update would fix it. We’ve since tried the latest firmware and the P1s continued to over-read, albeit by a slightly reduced margin of 5%. Such errors shouldn’t have reached production – consistency is everything.
- Read the full PowerTap P1 review: “Appealing price and practicality but let down by the performance and bulk”
How they compare
|Quarq Elsa RS||Stages Dura-Ace||Rotor INpower||SRM Shimano||Verve Infocrank||power2max Type-S||Garmin Vector 2||PowerTap G3||PowerTap P1|
|£1,049 / $1,399||£799 / $650||£500-750 / $779-1139||£1,999 / $2,199||£1,149 / $1,399||€690-1,590 / $610-1,490||£1,200 / $1,300||£499 / $600||£999 / $1,199|
|781g (w/ rings)||+30g||574g||900g||831g||790g||363g||329g||429g|
|L/R: calculated||L/R: no||L/R: no||L/R: no||L/R: yes||L/R: calculated||L/R: yes||L/R: no||L/R: yes|
|8 models||13 models||6 models||15 models||1 model||15 models||2 models (dual or single)||4 models||1 model|
|DIY battery swap: yes||DIY battery swap: yes||DIY battery swap: yes||DIY battery swap: no||DIY battery swap: yes||DIY battery swap: yes||DIY battery swap: yes||DIY battery swap: yes||DIY battery swap: yes|
|2032 battery / 500hrs||2032 battery / 200hrs||LR44 battery / 300 hours||Internal battery / 3,000hrs||LR44 battery / 500hrs||2450 battery / 400hrs||2032 battery / 175hrs||2032 battery / ‘months’||AAA battery / 100hrs|
|* battery life figures are what each company claims|
The power meter market is booming and moving fast. This means that previously well-rated meters, such as the PowerTap hub, can get pushed down the order and new products, such as the pedals, can be rushed to market too soon – both had glitches, frequent firmware updates and poor data that suggest more R&D time was needed.
We had high hopes for readily transferable accurate meters but we were disappointed. The Stages Dura-Ace 9000 was faultless on test, affordable and very light. It’s an ideal first buy. However, a single-sided meter simply cannot provide such accurate data and that’s the primary goal so it misses the top step of the podium. The SRM comes in third, its excellent performance mitigated by its high price and the continuing absence of a replaceable battery and left/right measurement. The Verve Infocrank really impresses but, like the SRM, has some trade-offs.
We have a clear winner and it’s the slick, light and dependable Quarq Elsa RS.
For more information on what to look for in a power meter, take a look at our Buyer’s guide to power meters.