Review: My experiences with the FSA Powerbox power meter

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This post is a quick review of my very short experience with the FSA Powerbox. I had the Powerbox installed for 1 ride before deciding that it wasn’t going to work with my BB86 bottom bracket, despite FSA’s advertising to the contrary. The power meter itself is actually very good, but in my opinion it is misleading for FSA to advertise it as fully compatible with BB86 and similar 24mm bottom brackets.

About the powermeter

The FSA Powerbox is essentially a rebranded Power2Max NGECO, which is itself an extremely good powermeter at a very competitive price. FSA essentially rebranded the NGECO and packed it up with proprietary FSA chainrings, essentially locking you into the FSA ecosystem. This is a negative for many people, but I found FSA chainrings to handle shifts very well, so I didn’t mind. FSA rings are also not too expensive, so no problems there.

Once installed, the Powerbox couldn’t be easier to set up. It turns on as soon as it detects movement, and is picked up by ANT+ devices immediately. No complicated phone-based setup here, it just works out of the box. Other features like auto-zeroing and temperature calibration make this meter competitive with meters much more expensive. Connectivity was great, with no dropouts during my test ride. Data seemed consistent and reliable. The NGECO is one of the best power meters on the market right now, so it makes sense that the Powerbox would perform similarly well.

Fitting the powerbox

My problem with the Powerbox is its 30mm crank axle. Many bikes, including my Ultegra-equipped Giant TCR, are built to accept 24mm cranks. To get around this, FSA has developed a BB86 to BB386evo (FSA’s proprietary bottom bracket size) “adapter”. This little piece of hardware is essentially just a weird-sized bottom bracket, small enough to fit my frame but with a large enough hole to accept a 30mm crank axle.

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Once I got the bottom bracket adapter installed, I ran into two basic problems with the setup.

First, the bottom bracket was stiff. Not unacceptably stiff, but definitely not as smooth as the BB86 Shimano bottom brackets I was used to. After doing some reading online, I learned that the adapter used two rows of tiny ball bearings rather than the typical one row of large bearings. This leads to a stiffer bottom bracket that is also prone to wear out early, sometimes only getting 3000-4000 miles before wearing out. Depending on the rider, this could mean changing the bottom bracket every season, which might be unacceptable to many. I accepted this because the Powerbox was already such a good deal, and I could afford a few bottom brackets (at $50 each) because I was saving so much to begin with.

The second problem involved wave washers. The FSA bottom bracket standard is designed to be slightly narrower than the crank axle width. To fill the extra 2mm of play, FSA employs a small wave washer that sandwiches between the non-drive crank arm and the bottom bracket, exerting a small amount of preload on the dust cap of the bottom bracket. Wave washers are widely available online, even in the 30mm axle size, but these washers are too wide for the FSA BB86-386evo adapter, sitting on the outer shell rather than pressing on the dust cap. This freezes the washer in place, adding an unacceptable amount of friction to the system. The adapter reportedly comes with a compatible wave washer, but mine was missing, and I couldn’t find an appropriately sized one anywhere.

What next?

So here I am with a power meter that just won’t play nicely with my bike. I decided to sell it and put the money towards the well-reviewed Assioma Duo pedal-based power meters. These are theoretically just as accurate, provide better left-right power data, and are transferable between bikes.

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Training with power is the next big step in my racing career, and I hope that the investment will pay off.

Follow me on Strava at https://www.strava.com/athletes/128938!

 
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