Best power meters: everything you need to know before you invest

Everything you need to know about the best power meters, including what they are, key features, and how to use them as well as our pick of the best

power meter
A power meter allows you to measure your training thresholds more effectively –and to keep track of how your fitness is progressing (Photo: Chris Catchpole)
(Image credit: Chris Catchpole)

If you want to get the most out of your training then getting the best power meter is the ideal tool to quantify your workouts.

As ever, the best power meter for one rider isn't necessarily the best power meter for the next. It all depends on how you intend to use it, your bike, your bike placement options, your budget and if you want to use the power meter with more than one bike.

We start this guide with our immediate product recommendations, and then we will provide you with an in-depth guide into understanding more about one of the most important technologies in cycling.

How does each power meter measures power? What does power actually mean? How it power calculated? These questions are answered below and there's even a helpful link to help you get the most out of riding with power.

Best power meters reviewed

best power meters

Best crank based power meter

Specifications
Accuracy: ±1.5%
Reading type: Right and left leg
Battery type: Coin cell
Reasons to buy
+Price+Easy to install+Reliable+Accurate
Reasons to avoid
-Not ideal for swapping between bikes

A winner in our 2019 Editor's Choice awards, the Quarq proved to be accurate, durable and reliable, without being anywhere near one of the most expensive on the market.

It's good to know that while we tested the carbon version, there's also an alloy Quarq DZero power meter for nearly half the price.

Our tester escaped dropouts and power spikes during testing, and found the data reliable - reading about four watts above a Wahoo Kickr, which is a reasonable number accounted for via drivetrain losses.

The Quarq DZero is a solid unit for those seeking easy, reliable, and accurate numbers from a power meter.

Read more: Quarq DZero power meter review

best power meters

Best high-end crank-based power meter

Specifications
Accuracy: ±1.5%
Reading type: Right and left leg
Battery type: Coin cell
Reasons to buy
+Durable+Consistant readings
Reasons to avoid
-Battery housing hard to access

The S-Works cranks from Specialized come fitted to some of their top-end bikes, pre-installed, but the unit is available aftermarket, too.

Specialized has used the technology created by 4iii - but it has housed it within its own external crank, with a major focus on ensuring sufficient waterproofing.The strain gauge is within two black pods, on the inside of the cranks, which make these duel sided and weigh just 15g.

We found the unit reliable and didn't suffer with dropouts or power spikes, with the whole experience close to flawless. The only downer was that crankset installation was a bit fiddly.

If you find the price tag of the full carbon S-Works version a tad out of your price range, it's good to know that there's also an Ultegra version for under half the price.

Read more: S-Works Power Cranks review

best power meters

Best rechargeable crank-based power meter

Specifications
Accuracy: ±2%
Reading type: Right and left leg
Battery type: Rechargeable
Reasons to buy
+Reliable overall readings+Easy to calibrate+Looks great+Long battery life/rechargeable
Reasons to avoid
-Expensive-Left/right readings inconsistent

Shimano's first crack at a power meter is a reliable and easy to use dual-sided meter that looks the business.

We've listed it in our 'best of' guide because it's an option under high demand. Touches like the USB recharging port are great, and tester Richard Windsor found it was easy to calibrate and change batteries.

Being a first-generation, it did expose some flaws, such as occasionally the R/L power readings coming through as 100% from the left leg. However, this could be fixed by performing a quick zero offset and the overall reading always appeared accurate. 

We'd expect some of its issues to be rectified through updates.  But for such a high price, it's worth considering if other options might suit your needs and save you some cash, too.

Read more: Shimano Dura-Ace R9100-P power meter reivew

best power meters

(Image credit: Cycling Studio)

Best crank-based power meter for versatility

Specifications
Accuracy: ±2%
Reading type: Right and left leg (with upgrade)
Battery type: Coin cell
Reasons to buy
+Reliable+Accurate+110 BCD across chainring sizes+Both leg reading compatible+Frequent self calibration+Ease of setting up
Reasons to avoid
-There are lighter power meter options-30mm spindle only

With its comprehensive range of chainrings, a power meter is a natural extension of its product portfolio for FSA. It paired up with German power meter experts Power2Max to develop the Powerbox crank-based power meter.

We got hold of the alloy FSA Powerbox for our test, but there's also full carbon versions available too, although expect to pay about double the price.

When we tested the Powerbox, we found that it was accurate and reliable and also coped well with the odd dousing with a hose pipe. It's ANT+ and Bluetooth compatible, comes in carbon and alloy versions and with a wide range of chainring size options, including super compact options.

Read more: FSA Powerbox power meter review

Best power meters

(Image credit: Cycling Studio)

Best power meter pedals

Specifications
Accuracy: ±1%
Reading type: Right and left leg
Battery type: Rechargeable
Reasons to buy
+Reliable+Rechargeable+Waterproof (so far)+Value for money
Reasons to avoid
-Pedal weighting

These pedals provide reliable numbers for the entirety of the testing period and didn’t have any problems connecting to the head unit, computer, or the companion phone app. The pedals are USB rechargeable via a magnetic connection, meaning no fiddling with rubber seals and ports.

The pedals provide some novel metrics, such as the amount of time you’ve spent pedalling out of the saddle and your platform offset – the degree to which you pedal with one side of your foot. More common metrics such as left-right balance are also present, although a cheaper single sided version is available which doesn’t have these capabilities.

Stopping the pedals getting a perfect 10/10 is the unfortunate pedal weighting, which does make clipping in and out a little more difficult than with other systems. If fast-starting crits are your thing, then that might be a concern. The Look cleat system is used on these pedals.

Read more: Favero Assioma Duo Pedals review

best power meters

Best power meter pedals for robustness

Specifications
Accuracy: ±1.5%
Reading type: Right and left leg
Battery type: AAA (lithium)
Reasons to buy
+Battery housing+Sturdy design+Robustness
Reasons to avoid
-Weight-Aesthetics

PowerTap's P2 pedal gives an accuracy rate of ±1.5% and when we tested the P2’s they proved to be a reliable training partner, with no data issues after 50 hours of riding.

These power pedals are not the lightest out there, weighing in at 398g with batteries—but the added weight comes in the form of a robust and sturdy design. The P2 pedals also incorporate a strong rubber seal as further weatherproofing and this always sat flush.

I did find that when heading off for a ride it sometimes took me a little longer than normal to locate my pedal with my foot. I put the strange sensation down to the way a normal pedal spins freely on its axle, whilst the P2s seem to present quite a bit of stiction which means they don't flip so easily when you nudge one with your foot.

Read more: PowerTap Quarq P2 power meter pedals review

Garmin Rally pedals

(Image credit: Dan Gould for Future)

Specifications
Accuracy: ±1%
Reading type: Right and left leg
Battery: LR44
Reasons to buy
+Reliable+Weather-resistant +Aesthetics 
Reasons to avoid
-Expensive-Most multi-discipline riders change bikes more often than it is practical to change spindles 

Garmin's Rally pedals are a progression from the Vector 3. They've seen some notable improvements, firstly, a better battery door design which appears  to eliminate issues with water ingress. Secondly, clever engineering means that you can swap the spindle between pedal bodies - using RS (Shimano), RK (Look) and XC (SPD-SL) style pedals and keeping the same power meter unit. 

The pedals look great, and our tests showed they worked extremely well, providing accurate readings with no frustrating drop outs or spikes.

These lost marks because they're a lot more expensive than the competition, and changing the spindle is a fairly fiddly job, that we don't expect multi-discipline riders would do as reguarly as many swap bikes.  

best power meters

Best power meter on a budget

Specifications
Accuracy: ±1%
Reading type: Left leg
Battery type: Coin cell
Reasons to buy
+Price+Easy to fit+Ridiculously light+You can account for left/right imbalance++Scale factor adjustment
Reasons to avoid
-Left side only not for everyone-We noticed some inaccuracy at high intensity

4iiii has delivered a reliable and inexpensive left-side crank that only adds 9g to the weight of the crank - including the battery.

It only measures left leg power, but with the 4iiii Precision, you can adjust the scale factor to account for a known imbalance in your power output between your legs.

Our testing found that it is sufficiently accurate and consistent, and we experienced no issues with regard to water ingress.

Read more: 4iiii Precision power meter review

best power meters

Best for reliability

Specifications
Accuracy: ±1.5%
Reading type: Right and left leg (combined)
Battery type: Coin cell
Reasons to buy
+Reliable+Good warranty+Accurate+Tried and tested design
Reasons to avoid
-If you use separate wheels for training and racing, you may not always have power

Any cyclist who's served a bit of time will agree that a PowerTap hub-based power meter was once the gold trophy of cycling widgets and on every rider's wish list. They've been overlooked in recent years, their lack of popularity largely comes down to the way they limit wheel swapping between training and competition. Increasingly hard to track down nowadays, Powertap hub power meters still have a huge fan base and no Best Power meter buyers guide would be complete without one.

We've really rated the Power Tap G3 hub for years, and still consider it the gold standard of power meters, highly recommending its overall reliability. Battery changes can be a bit fiddly, but that means the unit is incredibly watertight - which results in next to zero problems. It's a shame you don't get left/right power but not a deal-breaker.

The hub weighs 325g, so it does add a bit of weight in an uncomfortable place at the rear wheel, but it's not a huge price to pay for detailed and trusty numbers.

Read more: PowerTap G3 hub review

Power meters explained

A power meter is a device fitted to a bike that measures the power output of the rider.

Strain gauges deflect slightly when a force is applied. By measuring this torque and combining it with angular velocity, power (measured in watts) can be calculated. Some riders swear by regularly testing their functional threshold power as to measure how training is going. You can find out what is FTP in cycling and how to improve it on our dedicated page.

The math: power (W) = force x distance / time

Watts are the energy required to a move a mass a certain distance in a known time period. 1W = 1Nm/s in other words to move one Newton one meter in one second requires one watt of energy.

So in bike speak, the mass is you plus your bike, and the distance is the ground covered.

Moving a bike, though, is a far more complicated scenario, as its resistance to motion is far from consistent.In layman's terms, then, this equates as: power = force x velocity

And that is the key to understanding how a power meter works. It's essentially applying that equation to a given part of the bike - be that BB axle, crank, hub, pedal axle etc.

Accurate measurement of this force is one of the biggest challenges power meter manufacturers face, placing the upmost importance on the smallest of details such as the placement of the gauges, the quality of the gauges themselves and even the temperature of the measured material.

>>> Best smart turbo trainers

How do the best power meters work?

Currently, the best power meters can be placed in five key areas of a bike and how they work will depend on their location, although they will all use a strain gauge of some kind.

Of course, each has their own advantages and disadvantages.

Hub-based systems such as the PowerTap G3 are amongst the most simple power meters on the market. With fewer forces acting on the strain gauges, many engineers regard the hub as the most accurate location to measure power.

Power measurement will be slightly lower here than on a pedal or crank system as you're measuring what is left, post drivetrain losses. It also means your power output can be a bit lower if your drivechain is very dirty or worn.

Bottom bracket systems can be accurate and low maintenance. However, installation is more difficult and is made all the more complicated by the varyingbottom bracket standards available today.

best power meters

Factor in that a system of this type may not fit your bike and it is also likely to mean you have to run a different brand chainset to the rest of your groupset. Examples include Rotor INPower.

Chainring based power meters can be very accurate but it is worth factoring in that they don't actually measure individual left/right power, although they can estimate it.

Similar to bottom bracket systems, they are not as easy to swap between bikes, unlike pedal-based systems, and there can be compatibility issues. Examples include the fabled SRM (the most popular choice amongst pro riders), Power2Max and Quarq.

Crank arm-based systems can be relatively easy to swap between bikes, too. Like pedals, they have the potential to be single or double-sided and popular examples include the Stages crank arm and 4iiii precision meter.

Pedal-based systems are easy to fit and change between bikes, but can be less accurate owing to the complexity of the force measurement. What's more, being exposed makes them at greater risk of damage.

Popular examples include Garmin Vector and Look/ SRM Exakt pedals. Power meters of this type can also be single or double-sided.

Single, double and combined power meters

Single-sided power meters

You can buy single-sided power meters that measure power from one side, usually the left, and then double the reading to estimate your total power output from both legs.

best power meters

A single-sided only measurement means doubling a single legs power may not be a fully accurate representation of your power, but it can mean they are more affordable.

It may be worth checking if you have significant imbalances before opting for a single-sided meter. Note a 48/52% balance between legs is common.

Combined power meters

These units effectively combine the power from both right and left legs and do not measure it independently. An example would be a PowerTap G3 hub or SRM.

Note that these systems, although accurate, will not differentiate which leg the power comes from.

Left/right side independent measurement

This is found on more modern and more expensive power meters that have gauges in multiple locations, such as pedals and some crank-based units.

This can be useful in establishing if you have an imbalance (one leg much more powerful than another) and for working on pedalling technique. It can also be used ifyou are recovering from a single leg injury.

This is limited to power meters that measure power in more than one location, such as pedals, but also more expensive crank-based units, like Rotor 2InPower.

What Power meters work with Garmin and other cycle computer connectivity

Everything rated here and the vast majority of power meters transmit via ANT+, allowing them to connect to most bike computer systems, including Garmin.

Newer power meters are also offering Bluetooth Smart connectivity - a handy tool for connecting to indoor training apps such a Zwift and Trainer Road, or smartphones, as well as practicalities such as updating power meter software.

Our guide on the indoor training apps for cycling compares the best on the market and helps you identify what one you are most suited too. If you are wondering about power meters and turbo trainer compatibility, our page on best bike turbo trainers includes the latest models, although they can prove tricky to get hold off.

If the current climate means slim pickings on indoor trainers, or finances mean having to choose one or other, you can always bypass the smart trainer all together and just use a power meter and simple turbo trainer. You'll need a couple of other sensors but can still work out as a much cheaper zwift set up and you have the bonus of outside use once warmer weather a less travel restrictions apply.

Do power meters measure cadence?

Yes, even if you are using hub or bottom bracket based power meters, there will be the supporting software to enable you to measure cadence. Although pedal and crank based power meters will have an integrated cadence measure.

Are power meters worth the money?

There are lots of schools of thought about how to train and race effectively. Some people swear by tracking data, others steer well clear, but as with most things in life, most think it's about striking the right balance. Our feature on using a power meter in training is a really great insight in to what the experts say, acknowledging the best power meters as helpful tools, but not to loose touch with your rider instincts.

Why are the best power meters so expensive?

There are an incredible variety of power meters now on the market, which has helped their popularity, volume of sales and therefore help bring the prices down. However, it's still very much a developing technology, which has to be accounted for in the end price.

From our experience, its a 'you get what you pay for' product. The best power meters will have invested significant amount of research and development in ensuring that the end product is consistently accurate, robust enough to withstand forces and harsh environmental conditions and develop the supporting software.

Entry level - typically £250-£400/$300-$500

best power meters

At this price you are likely to get a single-sided measurement that doubles the reading to estimate both legs. PowerTap hubs are also available at this price, as are Stages 105 crank, the Powertap Hub and the Vector 3.

Mid-level - typically £550-£800/$700-$1,000

best power meters

Mid-price starts to see pedal-based systems and dual-sided meters. Crank and chainring systems also become available. Professional athletes are increasingly using meters at this price point. PowerTap P1 Pedals is a fine example.

Top end - £900/$1,200 +

At the top of the market, we find dual-sided measurement and crank and spindle based systems. Examples include the Rotor 2InPower.

How to use a power meter

If you want to learn about how to ride with a power meter, it's worth reading our guide on how to train with a power meter. It has lots of useful information about how get the most out of your gadget and how to apply the numbers to your training.