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The single CR2032 battery on the Stages Cycling StageONE power meter is user replaceable. Claimed battery life is at least 200 hours of use.
$699 crank arm unit brings power to the masses
This article originally published on BikeRadar
Boulder, Colorado-based company Stages Cycling will launch at Interbike the new StageONE, a true direct-measurement power meter that weighs just 20g, is claimed accurate to within +/- 2 percent, and costs as little as US$699 – oh, and it seems to actually work, too.
The StageONE is a single-sided power meter that is built into slightly modified left-hand crankarms and directly measures power via a strain gage array, custom electronics, and a special algorithm that not only filters out non-applicable forces but also interpolates total left-plus-right output. Despite the StageONE being a new product, it's based on a simpler design Stages Cycling has already thoroughly validated on over 7,000 similar systems built into commercial exercise bikes but in a much smaller, lighter, and sleeker package.
Small, light, and sleek it is for sure – claimed weight for the entire system is just 20g, it adds less than 10mm to the inner profile of the crankarm, and once installed (with no holes or structural changes required, mind you), it's barely noticeable with virtually zero effect on a bike's aesthetics. Since the system is based on a left-hand crankarm exclusively, it should also be very easy to transfer between multiple bikes with no effect on the drivetrain adjustment and no recalibration when swapping chainrings. Users will still be able to retain power measurement when swapping between racing and training wheels or different pedals, too.
As if that weren't enough, Stages Cycling claims the StageONE incorporates automatic ambient temperature compensation to retain accurate readings, it measures cadence without having to install a separate magnet on your bike anywhere, it transmits data via both ANT+ and Bluetooth Smart protocols for maximum compatibility with both existing head units and many popular smartphones, claimed battery life is more than 200 hours, and the standard CR2032 battery is easily replaceable at home.
And for those keeping track, the StageONE is completely manufactured in the United States – even the plastic casing – with the lone exception of the circuit boards, which are currently printed in Taiwan.
That feature set would be impressive for any direct-measurement power meter but that the StageONE is priced so relatively inexpensively is merely icing on the cake. According to Stages Cycling vice president of product development Doug Crawford, the goal of the StageONE is simply to "bring more people into power."
You can't have it all – or can you?
Stages Cycling readily admits that it's not necessarily trying to go head-to-head with established players such as SRM, Powertap, and Quarq in terms of outright technology, instead preferring to go after so-called 'blue collar' riders who merely want a consistent means of tracking progress for training purposes.
Along those lines, the StageONE does hold a few disadvantages. Being a left-only system, it relies on a mathematical algorithm to calculate total power output so it can't display more advanced features such as left/right power balance. Moreover, it also assumes that a rider's output will be the same between both legs.
BikeRadar was granted an exclusive first test ride on the new StageONE during a visit to the company headquarters and while overall correlation to the Powertap hub we had installed concurrently was very impressive, a quick analysis of our hour-long session data also appeared to reveal that this particular tester pedals harder with his right leg.
Stages Cycling will also have to convince some riders to ditch their existing carbon crankarms – or at least just one of them. While StageONE's January 2013 release date will include an impressive fourteen models – even including downhill, BMX, and track cranks – inherent problems with hysteresis associated with composite construction means the StageONE will only work with aluminum arms.
You can get a StageONE power meter on any major crank arm you like - as long as it's aluminum
That being said, company marketing director Matt Pacocha [who, in the interest of full disclosure, most recently worked as BikeRadar's US editor] says swapping from a carbon fiber Truvativ X0 crank to an aluminum X9 adds only 36g in total.
In addition, Stages Cycling estimates the StageONE will fit on roughly 90 percent of road and 'cross frames but some full-suspension mountain bike configurations – and especially downhill bikes – could present clearance issues (Stages Cycling says it will post a constantly updated compatibility list on its web site).
Such a construction method also begs the question of retrofits. However, Stages Cycling builds every power meter exclusively into new crankarms sourced directly from the manufacturers and currently has no plans to offer retrofits for buyers that already own compatible units.
Even at such a relatively inexpensive price, perhaps the biggest hurdle Stages Cycling will have to face is convincing buyers that it isn't just some plastic box glued on to a crankarm. Stages Cycling wouldn't allow us to photograph the bare inner workings but interested parties should remind themselves that the casing merely encloses the more intricate and complex workings hidden inside.
"It's high-tech but simple," Crawford told BikeRadar. "It's elegant and it looks simple but that's just refined engineering."
If the StageONE indeed can offer consistent readings as promised, though, none of those modest potential pitfalls will matter. Cyclists will finally be able to use directly measured power data for more effective training at a price point previously restricted to the secondhand market (or computed solutions such as iBike) and depending on how the StageONE is received, none of us may ever look at power meter pricing the same way ever again.
The complete model and pricing run-down is as follows, based on crank manufacturer:
*Hollowgram SI SL (pre-2012, road/mtn power meter only), US$TBD
*Hollowgram SI SL2 road, US$TBD
*Hollowgram SI SL2 mountain, US$TBD
*Hollowgram SI road, US$TBD
*Hollowgram SI mountain, US$TBD
*Dura-Ace 9000, US$949 power meter; US$1,349 complete crank
*Dura-Ace 7900, US$899 power meter; US$1,299 complete crank
*Ultegra 6700, US$799 power meter; US$1,099 complete crank
*105 5700, US$699 power meter
*Dura-Ace Track, US$899 power meter
*XTR, US$899 power meter
*XT, US$799 power meter
*Saint, US$899 power meter
*X9 GXP, US$699 power meter; US$899 complete crank (Compatible with X7, X9, X0, XX [166mm Q model], and many other Truvativ models)
*X9 BB30, US$699 power meter; US$949 complete crank
*Rival OCT GXP, US$699 power meter; US$899 complete crank (Compatible with Apex, Rival, Force, Red, Truvativ Omnium (track), and many other Truvativ models)