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FSA Powerbox Alloy Chainset



Accurate and reliable power meter at a very competitive price

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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FSA has jumped into the power meter market by partnering with German company Power2Max to produce a crank-based power meter. Coming in at £599.95, the PowerBox Alloy Chainset is very attractively priced and is backed up by consistent and reliable performance.

The two companies have worked together in the past, but since the launch of its WE groupset FSA has stepped up its offering in the hugely competitive power meter market. PowerBox is available in two versions, either based on a Gossamer aluminium crankset, as tested here, or a K-Force carbon fibre option for £1,199.95. The prices include the aluminium chainrings, with a choice of ratios available.

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FSA is using Power2Max's Type-S power meter, not its latest offering, but it's a power meter that has been proven in professional races over the years with several WorldTour teams, so you know it is built to last and accurate enough for the pros.

In detail

It's powered by a CR2450 coin-style battery hidden under a large rubber cover on the spider. Battery life is claimed to be good for 400 hours or 12,000km – I've not run close to that yet.

The battery is easy to replace: just flip that rubber cover, pop the battery out and replace it, and you're good to go. Any concerns it might not be adequately protected from the elements proved unfounded during testing in torrential rain and under the hosepipe when washing the bike down after mucky rides.

FSA Powerbox Alloy Road Chainset - detail.jpg

The crankset is made with 6061 aluminium, 7075 aluminium CNC-machined chainrings and a BB386EVO 30mm axle. The BB386EVO 30mm axle could potentially limit compatibility in some instances, but there are suitable bottom brackets and adapters available to provide installation for most bike frames. The aluminium version is available with 170, 172.5 and 175mm crank lengths, the carbon version increases the range, from 165 to 180mm.

In use

I've been testing the new PowerBox for the last couple of months, a period of time that has allowed me to put the power meter through its paces in all sorts of conditions and long enough to uncover any hidden gremlins. I can report that there have been no issues at all, in fact performance has been flawless. I'm very impressed.

The PowerBox has delivered consistent power measurement at all times. The claimed +/-2% accuracy precision appears on the money during comparative testing with other power meters (a Wahoo Kickr and PowerTap P1 pedals) with no random spikes or anomalies to report.

It has worked consistently through large temperature fluctuations, the power meter compensating for any changes and preventing any drift in accuracy. Connectivity has been just fine via the ANT+ wireless protocol – Bluetooth Smart is going to be added as an update later this year, which increases the range of compatible devices.

Installation was a cinch. The cranks and chainrings are supplied preassembled so it's simply a case of removing the old crankset and sliding the PowerBox into place. Within a few minutes, it was paired with my Garmin Edge and ready to ride.

FSA Powerbox Alloy Road Chainset - reverse side.jpg

Okay, so it's not quite as easy as fitting one of the growing number of single-sided or pedal-based power meters, and swapping between bikes is obviously a drawback of a crank-based power meter, but if you only want or need power measuring on one bike, it's not a problem.

There's never a need to calibrate; the PowerBox has an Auto Zero function so you don't have to manually zero offset it before a ride, and it does this every time you stop pedalling for three seconds. The power meter goes to sleep when not in use and wakes up within a couple of pedal revolutions. You can also change the chainrings without affecting the calibration. An integrated accelerometer provides cadence data so no attaching magnets needed.

> Buyer's Guide: How to choose a cycling power meter

FSA makes excellent chainrings and they presented no issues on the SRAM Red-equipped bike I used for testing the PowerBox. The 7075 aluminium chainrings, compatible with 10 and 11-speed Shimano and SRAM groupsets and 10-speed Campagnolo, provided excellent shift quality – smooth and precise at all times. As well as the compact 50/34t tested here, FSA offers 53/39 and 52/36 options, using the same 110mm BCD (bolt circle diameter).

FSA Powerbox Alloy Road Chainset - detail 2.jpg

Any issues? None whatsoever. Performance was superb. Being critical, the PowerBox in this aluminium guise is no featherweight: the driveside crank is 669g. The carbon PowerBox drops that weight down to 585g but it's nearly double the price, so unless you're a weight weenie I'd stick with the alloy version.

But when it comes to price, the PowerBox has its rivals licked. An SRM is going to set you back £1,800, Pioneer's Dual Leg power meter is £1,100 and the Verve Infocrank is £1,149. The Quarq DZero 11R comes close at £693 but that doesn't include chainrings. So £600 for the power meter and chainrings represents a good buy. And a bit of shopping around reveals it can be had for less.

All things considered, the FSA PowerBox is a highly impressive power meter, and the price, performance and reliability make it extremely easy to recommend.


Accurate and reliable power meter at a very competitive price

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Make and model: FSA Powerbox Alloy Chainset

Size tested: 50/34t, 172.5mm, 110mm BCD

Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

FSA says: "FSA's ROAD PowerBox Alloy Crankset employs a P2M convertible spider design for multiple chainring options. FSA's alloy arms and BB386EVO spindle mated together produce a very lightweight, extremely versatile power meter crankset available with a double chaining configuration."

Tell us some more about the technical aspects of the product?

FSA lists these features:

Cold forged AL6061/T6 aluminum crank arms

BB386EVO 30mm AL 7050 alloy spindle fits every frame (purchase BB separately)

AL7075 100% CNC chainrings

Chromoly chainring bolts

Fits Shimano and SRAM 10-11 speed systems

Spider-based power sensors provide total power output measurement of both legs, with Left & Right leg output analysis available with system upgrade*

Bluetooth connectivity available with system upgrade*

*System upgrades (consumer in-app purchase) will be available from September 2017, Costs and complete features of the system upgrade to be announced.

Rate the product for quality of construction:

First class construction quality, no complaints or issues.

Rate the product for performance:

Works well all of the time, what more do you need. It's accurate and consistent, the two key qualities you want in a power meter.

Rate the product for durability:

Not had any problems at all.

Rate the product for weight (if applicable)

It's not particularly light.

Rate the product for value:

It's about the same price as a Stages Ultegra single-sided power meter, but the PowerBox measures power at the crank spider and provides left and right leg power measurement.

Tell us how the product performed overall when used for its designed purpose

Delivered consistent and accurate power measurement in all conditions.

Tell us what you particularly liked about the product

Worked flawlessly all of the time.

Tell us what you particularly disliked about the product

The weight, if I'm being a bit picky.

Did you enjoy using the product? Yes

Would you consider buying the product? Yes

Would you recommend the product to a friend? Yes

Use this box to explain your score

Power meter prices are gradually falling, and while not cheap, the new FSA PowerBox Alloy is a seriously good option at this price.

Overall rating: 9/10

About the tester

Age: 31  Height: 180cm  Weight: 67kg

I usually ride:   My best bike is:

I've been riding for: 10-20 years  I ride: Every day  I would class myself as: Expert

I regularly do the following types of riding: road racing, time trialling, cyclo-cross, commuting, touring, mountain biking

David worked on the tech team from 2012-2020. Previously he was editor of and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds, and you can now find him over on his own YouTube channel David Arthur - Just Ride Bikes

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