Cycling Power Meter Guide

Updated: 21st July 2021


This page covers my 15+ years of experience of installing, testing, racing, and breaking power meters across road, time trial, and now gravel bikes. 

Every power meter I’ve used is listed below. The format of this guide is to provide a brief overview of my experience with each. I’ve covered the majority of these in-depth over on YouTube. This post won’t go into that level of detail. It will however help you narrow down your options. 

This guide will be updated on a regular basis.


 

Pedal Based Power Meters

 

Favero Assioma DUO

Favero’s second generation power meter pedal (BePro was their first). I’ve performed hundreds of comparative tests with the Assioma DUO (and UNO) and continue to use them today as a reliable source of power indoors and out. My original set from May 2018 are still holding charge as well as first use. Regular firmware updates from Favero have improved features and resolved corner-case bugs, with auto-zero being introduced in firmware 4.75.

You will have to switch to their Look-compatible three bolt cleats (floating or fixed options) and have their proprietary USB charger at the ready to top them up. Unofficial hack allows use of Shimano SPD dual sided pedal bodies. 

One of my trusted go-to power meters for general riding and comparison tests indoors and out.

Verdict: Highly recommended. These pedals have yet to give me any reason not to give these a huge tick of approval. 

Links:
GPLama Assioma DUO Review
Favero Assioma MTB/SPD Pedal Hack How-To
Buy Favero Assioma DUO (Amazon US)

 


Favero Assioma DUO-Shi (Shimano Road SPD-SL)

Using the exact same spindle, battery, electronics, and firmware as the Assioma the DUO-Shi has two modifications that allow the user to install their own compatible Shimano SPD-SL Road pedal bodies. 

Technically speaking, everything remains the same as the original Assioma offering. Favero state the DUO-Shi requires a different calibration process at the factory for accurate power readings, so there’s no upgrade kit for those with Look Keo style Assioma who want to switch to the SPD-SL pedal body.   

The 65mm pedal Q-Factor means your stance width will be increased ~26mm with these pedals. (The original Assioma are 54mm. Shimano SPD-SL 52mm). This is a HUGE increase and one bike fitters rarely prescribe people who have a legitimate reason to adjust their road bike fit. 

Verdict: No. A very reluctant no. The Assioma are one of the best performing power meter pedals but the DUO-Shi Q-Factor is just too wide. 

Links:
GPLama Assioma DUO-Shi Review

 


PowerTap P1/P2

Note: Discontinued product as of March 2021.

I’m combining these two products together because they are virtually the same product. The P2 has had a few grams shaved under the cleat plate and comes in ‘nude’ silver only.Even with the weight savings of the P2, these nuggety pedals are now heavy by today’s power pedal standards (P1 ~437g / P2 ~400g) 


The P1 was the first ‘no funky install required’ power meter pedal. I used a set from January 2017 through to getting the Assioma DUO in May 2018. Reliable source of power if using ANT+. When connecting via Bluetooth these pedals are SINGLE SIDED only. This has caught a few people out. SRAM, the new owner of the PowerTap brand need to refresh this line to put the PowerTap P1/P2 back in the game. 

These also use Look-compatible three bolt cleats (floating or fixed options) but use a standard AAA battery which is easily sourced. 

Verdict: Maybe. If you can get a pair cheap and don’t mind having the little weighty nugget pedals on your bike. SRAM discontinuing this product line should also be noted. 

Links:
GPLama PowerTap P1 Review
GPLama PowerTap P2 Review
Buy PowerTap P2 (Amazon US)



Garmin Vector 3

In my opinion, the most discreet and best looking power meter pedal on the market. The Vector 3 was the first podless easy-to-install version of the Vectors, the previous versions requiring torque wrenches and awkward pod hardware. The Vector 3 pedals had a very rough start to life and a tough childhood. They’re the kind of power meter that ‘is known to police’ when you read about them being arrested in your local paper. My original set have been replaced by Garmin under warranty. The replacement set with updated battery housing/caps (their 4th attempt at a battery cap design) have performed well. 

Look-compatible cleats again for these power pedals but these are slightly different to those used on the Assioma or PowerTap P1. Batteries: Officially x4 SR/LR44 or a better option is x2 CR1/3N. They’re the only power meter on the market that supports the full suite of Cycling Dynamics metrics (Pedal Phase and Platform Centre Offset). 

Verdict:
A hesitant “YES”. I’ve switched my verdict given the performance of the Vector 3 with the CR1/3N batteries and the 4th generation battery housing. Proceed with caution on any pre-owned units. Make sure they have the latest battery housing. 

Links:
GPLama Garmin Vector 3 Review
Buy Garmin Vector 3 (Amazon US)
Buy CR1/3N Battery (Amazon US)



Garmin RALLY RS / RK / XC

Essentially the Garmin Vector 4, or more accurately the Vector 3.5. Almost everything about the pedal spindle is identical to the Vector 3 aside from the pedal body options. The Rally is available in Look Keo (LK), Shimano SPD-SL (RS), and Shimano SPD MTB style pedal bodies (XC). The ‘100’ denoting single sided, the ‘200’ being dual/double sided. These pedal body kits can be purchased on their own and installed on Vector 3 pedals. 

Shipping with the updated battery housing and a single CR1/3N battery. They’re still the only power meter on the market that supports the full suite of Cycling Dynamics metrics (Pedal Phase and Platform Centre Offset). 

Verdict:
It depends. I’m leaning towards a ‘no’ at this point. I have unresolved issues with what appears to be residual torque after really hard sprints on the Rally RS. This is ‘fixed’ by forcing a zero-offset calibration after the sprint. 

Links:
GPLama Garmin Rally RS200 Review
Buy Garmin Rally (Amazon US)
Buy CR1/3N Battery (Amazon US)


IQSquare Road Pedal (Left Only)

How the IQSquare story has unfolded gets more attention than the power meter itself. After two years and a design change, the product does exist. Well… they’ve delivered one to the Lama Lab for testing. To be brutally honest – The IQSquare road pedal (Left only at this point in time) has no stand-out feature other than price when compared to what’s already on the market. The conclusion from the testing both inside and out is that they were able to deliver a cheap and accurate power meter. The question remains as to what they’ll deliver backers, and how the still unseen dual sided options will perform.

Verdict:
No. And that’s a HARD NO. Even though the single pedal they sent over performed well, it’s a “NO” until until they prove they can deliver a product. It’s just too risky putting money down on a promise, not a product. I do not recommend pre-ordering until IQSquare deliver to all their Kickstarter/Indiegogo backers. 

Links:
GPLama IQSquare Power Meter: Details & Data [Single Side Road Pedal]
Look KEO Grip Cleats (Amazon US)


Spider Based Power Meters

 

Power2Max NG eco  

I finally put one of these power meters through the Lama Lab in mid October 2020 and wasn’t let down. The unit I had was a the Rotor 4 bolt 110BCD spider that I matched with a Rotor ALDHU crankset and DuraAce chainrings (meaning the standard 24mm spindle/bottom bracket didn’t need to be swapped out). The NG eco performed extremely well indoors and out and matched the other known-accurate power meters used well within the ±2% accuracy specification. With a ANT+ and Bluetooth Smart, 300hr battery life, auto-zero, and temperature compensation there’s a lot to like about this P2M unit. 

Verdict: Yes. Highly recommended.  

Links:
GPLama Power2Max NG eco Power Meter Review


 

Quarq (Specialized Spider)

I’ve had four of these power meters over the years across both road and TT bikes. Reliable data. I have no issues with the accuracy (power and cadence). And static weight calibration always kept them in check. These were ANT+ only units which you’ll be unlikely to find these days – however they were a great product early on that indicated Quarq could produce a quality power meter. 

The CR2032 battery lasted months. Installation of the spider was always performed by a local bike shop onto existing S-Works carbon cranks. 

Verdict: Yes. 

Links:
GPLama Quarq S-Works Calibration
Buy Quarq DZero Specialized Spider (Amazon US)



Quarq DZero DUB  

As with my previous Quarq experience, the DZero was spot-on from the first pedal stroke. ANT+ and Bluetooth support. The only issue I can come up with is a fudged/estimated pedal balance won’t be as accurate as two independent meters (pedal power meters). Other than that, I have no issues recommending this power meter for one of the best spider based power meters on the market. Uses a standard CR2032 battery with tool free battery swap. And you can use whatever pedals you like. The recent MagicZero auto-calibration feature is another feather in the Quarq cap. 

Verdict: Highly recommended. This power meter is something I can use as a trusted source of data for comparison tests. If a spider-based power meter is what you’re after, this is a well performing option. 

Links:
GPLama Quarq DZero DUB Power Meter Review
Buy Quarq DZero (Amazon US)



SRAM Force/Red AXS Spider (Quarq)

Effectively a four-bolt version of the Quarq DZero DUB with a 107mm BCD. See above summary of that unit. Ability to change chainrings is a bonus for this over the integrated chainrings on the SRAM RED Power Meter. Limited to SRAM Force/X1 chainrings due to the 107mm BCD.

Verdict: Highly recommended for those with FORCE or RED who want the ability to change chainrings themselves without replacing the power meter. 

Links:
SRAM RED/Force AXS Power Meter Spider: Details // Review
Buy SRAM Force/RED AXS Spider (Amazon US)



XCadey XPOWER-S Spider 

Produced by Chinese based company XCADEY. The cheapest spider based power meter on the market at this point in time. This model has a number of crank interface / BCD / chainring bolt configurations to choose from. First review unit was replaced after reporting low sprint watts. Second unit had issues with auto-zero (disabled in later firmware) and reading 5%-6% lower than two other known-good power meters. Scaling the XPOWER-S up to 105% within their app rectified this miscalibration. Other than that, once those issues were resolved the unit produced good numbers.

ANT+/BLE support means it’ll be compatible with anything indoors and out. 


Verdict: Yes, assuming the unit is correctly calibrated from the factory. I’ll be looking at getting another unit to verify calibration.   

Links:
XCadey XPOWER-S Cycling Power Meter: Details // Data Review



ROTOR INSpider 

The first spider based power meter from ROTOR with a 110BCD 4-Bolt chainring pattern. Compatible with their chainrings and Shimano 4-Bolt rings (8000/9100 range). Compatible with their modular crank systems (ALDHU / Vegast) giving the flexibility to choose almost any crank-length size you wish. Support for 24mm and 30mm spindles makes this an attractive alternative for bikes with Shimano group-sets who want to run a 24mm BB and Shimano chainrings. ANT+, BLE, and their own high-speed data mode supported. No issues with the reported accuracy indoors over multiple tests. Outside testing revealing something I wasn’t able to diagnose. With over 30 hours of data collected I was seeing the unit report -10W for periods of time, then falling back into line, then sometimes +10W. I was unable to explain or diagnose this one. Firmware 0.28 didn’t resolve this. The ball is with Rotor on this one for now.

Verdict: No. Even though the numbers indoors were brilliant and the 24mm BB compatibility with Shimano rings is a great option for people to switch to… I’m not able to use this meter as a baseline to compare others with. Yet.

Links:
ROTOR INSpider Cycling Power Meter: Details // Install // Data Review

 


Crank Based Power Meters


Rotor 2INPower

 
Accurate outside, reads a little high indoors. A number of us power meter propeller-heads noted this when performing comparative tests. Has an interesting 50Hz high-speed transmission mode which is only compatible when using their software indoors. Unit has a 200Hz sample rate at all times and is Q-Ring compatible. Rechargeable battery with a proprietary connector. 

With no resolution to why the unit read high indoors, I’d give this a miss. I’m not sure of the 2INPower DM model is any better, I haven’t seen any data from one of those units. 

Verdict: No. 

Links:
GPLama Rotor 2INPower Review
Buy Rotor 2INPower (Amazon US)



WattTeam PowerBeat G2/G3

WattTeam ceased operations in late 2018. Do NOT purchase these units new or pre-owned. New units require registration / authentication within their app which is now likely unsupported/orphaned. Consider other options. 

Verdict: No. 



Shimano Dura-Ace R9100-P Power Meter


Putting the facts on the table first to set the scene – Shimano made a crankset first and retrofitted strain gauges to it to call it a power meter. Shimano use the same externally placed strain gauge design as third party companies using their cranks as power meters (4iiii, Stages, Pioneer, Magene, X-Cadey, InPeak, etc). The R9100-P reads low on the right side. This has been independently tested and observed in a number of power meter reviews. The Left/Right R9100-P is covered in my report outlining the issues with R9100/R8000 Shimano cranks when used as power meters (specifically the right side having issues). 

Shimano defend the unit as being of a high standard and accurate, the independent datasets posted online indicate otherwise. I would not be surprised if Shimano redesign the right crank configuration for the next iteration of Dura-Ace (12 speed road?) to address this issue – maybe embedding the gauges within the crank and locking out third parties from using Shimano cranks as their power meter base. 

Verdict: No. Not a power meter I’d recommend. Let’s see what 2020 2021 brings from Shimano. They’d do well with a SPD-SL power meter pedal.

Links:
GPLama Shimano Based Power Meter Report
GPLama Shimano R9100-P Power Meter Review
Buy Shimano FC-R9100-P Power Meter (Amazon US)



4iiii Podiiiium (Dual Sided. Non Shimano) 

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Rechargeable pod version of the 4iiii meter mounted to a FSA SL-K Carbon crank. ANT+ and Bluetooth support. Quality data. Only issue I had was a few short power spikes on outdoor rides. The base crank wasn’t a Shimano R9100 or R8000 so there were no L/R issues that plague those power meters. This is a good indication 4iiii make a good gauge/pod, it just lets them down when suck onto a Shimano crank. Support for device tracking via Chipolo network (I can’t get this feature to lose/find 4iiii units in Australia….) 

Verdict: Yes. I’d happily use the FSA SL-K Carbon as a baseline meter for power comparisons. 

Links:
GPLama 4iiii Podiiiium FSA SL-K Power Meter Review



4iiii Precision (Dual and Single Sided – Shimano crank) 


Single Sided (Left) – Easy installation on a bike that already has Shimano cranks. ANT+ and Bluetooth support with tool free CR2032 battery. No issues with accuracy or quality of data. Limitation of being a single sided power meter (left power is doubled to give an estimated total power). Support for device tracking via Chipolo network (as with the Podiiiium, I can’t get this working properly). 

Dual Sided (Left/Right) – As above for technical specs but with the issues of Shimano R8000/R9100 right side cranks with external gauges. Not accurate enough for me to use as a reliable and accurate source of power to compare other meters/indoor trainers to.

Verdict: Split. I have no issues recommending the 4iiii Precision LEFT as a single-sided power meter. I’d stay away from the dual L/R. 

Links:
GPLama 4iiii Precision LEFT Power Meter Review
Buy 4iiii Precision LEFT (Amazon US)



Stages Gen III (Dual and Single Sided – Shimano crank)
 

stages-dura-ace-fc9100-l-r-dual-side-170mm-power-meter-52-36t-crankset-DR9-C6Very similar experience as with the 4iiii Precision. ANT+ and Bluetooth with a tool free CR2032 battery. Stick to Gen III or above due to the enhanced radio/signal strength. 

Verdict: Split. I have no issues with the LEFT single-sided Stages Gen III. The dual L/R doesn’t produce reliable results I can use in the Lama Lab for testing. Give the dual L/R a miss. 

Links:
GPLama Stages Gen III DUAL Power Meter Review
GPLama Stages Gen III LEFT (Single) Power Meter Review
Buy Stages Gen III (Amazon US)



Pioneer (Dual Sided – Shimano crank) 

SGY-PM910H ANT+ Only (older model)
SGY-PM930H ANT+/Bluetooth (current model)

Cut and paste my experience from above Shimano based power meters, and yes, both these dual sided units have that dreaded RIGHT Shimano crank issue. That aside, the Pioneer units have a high-speed data mode that’s compatible with their own head unit and Wahoo ELEMNT devices.

As of March 31st 2020, Pioneer have ceased operations in the cycling power meter and GPS head unit market. Shimano acquired the software assets (Cyclo-Sphere).

Verdict: No.



Magene P325 CS Power Crank 

Third generation power meter from Magene appearing on Kickstarter in November 2020 with a projected delivery date of December 2020. The dual-sided unit ships with their own one-piece spider/chainring setup that attaches to the Magene cranks via a SRAM 8-Bolt compatible interface.  

Rechargeable pods (200hrs usage), ±1.5% power accuracy (claimed), ANT+/BLE, 24mm spindle crankset. The P325 CS tested well under steady state efforts but appears to have problems with maximal sprints, out of the saddle efforts, and erroneous power data at random intervals due to cadence misreporting. The unit sent to me had incorrect pedal spindle drilling. See the video for details…. but it was a major problem! 

Verdict: No. As above, there were a number of fatal flaws with the unit they sent me for review. I’ve had no follow-up communication from Magene since publishing my review. I see no reason to recommend this unit. 

Links:
Magene P325 CS Power Meter: First Look Details // Ride Data Review


INPeak PowerCrank Gen II

54A7187-bialy-1Single sided (LEFT) Shimano crank power meter from smaller Polish based company. InPeak resolved a number of issues that were identified in my Lama Lab testing and really nailed things down with the release of firmware v1.11. ANT+ and Bluetooth support. Firmware 1.11 was producing quality single sided power data in my testing indoors and out. I’d have no issues recommending this unit if you’re looking at single sided Shimano based options. 

Verdict: Yes. 

Links:
GPLama InPeak PowerCrank GEN II Review (fw 1.11)
InPeak Official Website


Other (Hub, Spindle, Opposing Force, etc)


PowerTap Hub


Note: Discontinued product as of March 2021.

My first power meter way back in the day. This unit was the wired version as this was prior to ANT+ hitting the airwaves. I had a very bizarre issue with the first PowerTap hub where it’d drop signal if the unit was cooler than 16degC. That diagnosis took months to figure out…. PowerTap provided another unit and all was well. A year or so later I upgraded to the wireless 2.4GHz ANT+ compatible version. I had nothing to compare the numbers to at the time – but the data was clean and consistent. The newer PowerTap hubs (and the yet-to-be-seen G4) require a little more effort to install as they have to be laced into a wheel of your choice, or purchased as an already-installed wheel. This adds to the overall cost. 

Verdict: Maybe. Stick to the newer G3 and above if you’ve weighed up the total cost and are happy to roll with a rear-hub power meter. 


SRAM Rival AXS Quarq (Single Sided Spindle-Based)


Note: Testing still underway. Review video to be posted soon. 

Still under review in the Lama Lab and on the road. Single sided unit with a single AAA battery in the spindle. DUB bottom bracket / crankset compatible. Sold as a single LEFT crankarm and spindle, or a whole crankset. 1x and 2x options. Unit required scaling up by 6% and now matches an Assioma UNO nicely. Accuracy well within the stated ±3% spec in my testing after the scale-up.

Verdict: TBA. Looking good at this point but I need more answers from SRAM/Quarq as to the 6% scale-up requirement.
 


 

Currently Testing:

Sigeyi AXO Spider: Long term testing performed. Noticing a few minor offset drifting issues and differences in accuracy with each firmware updated. All units have been returned to Sigeyi for evaluation. They may provide other units in the future for further testing/review. No communication from them in a few months now.

Other Units I’ve used TBA: (I’ll update this page soon!)

Magene Ridge: Single and Dual. Shimano based. 
XCadey Single Sided (Early Model): ANT+ Only. Good power numbers. A few other minor issues.
ZWatt Zpider: Launched as a subscription service/hardware. Now a purchase/own product. 
SRM DA7800 Wired: Legacy unit. DA7800. Wired (no ANT+ or BLE). PCV.
SRM Pro Wireless: Octalink. ANT+. 
SRM Origin Carbon Road: Most expensive power meter I’ve tested. ANT+ only.


Units I have not had access to test/comment on: 
– SRM Exact (SRM MTB Pedals) 
– FSA PowerBox (Power2Max NGeco) 
– Specialized Power Cranks (based on 4iiii tech/partnership) 
– Older pedal power meters: Vector 1/2, BePro. (Old tech. Unlikely to cover these)
– Opposing force power meters (PowerPod)
– Power Estimating Apps/Head Units. 

More coming soon here… For now head on over my YouTube video archive for all my hands-on power meter coverage: https://www.youtube.com/user/gplama/search?query=Power+Meter

 

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