viernes, septiembre 21, 2012

Medidor de potencia de biela (cycling power meter in crank)

StageONE cycling power meter comes pre-installed on crank arm

By Enid Burns.September 19, 2012

Cycling power meters generally need to be affixed to the crank with wire ties, magnets, brackets or double-sided tape. The StageONE from Stages Cycling is a power meter that comes pre-installed on the left crank arm component of a bike. It uses a strain gauge and an accelerometer to capture power output data, which is transmitted via ANT+ and Bluetooth to compatible cycle computers and smartphone apps. Most important of all, it's makers claim it's cheaper than existing cycling power meters on the market.

The StageONE is sold pre-attached to 14 different aluminum crank models from Cannondale, Shimano, and SRAM, so installation is accomplished by replacing the left crank arm on the bike. It uses ANT+ and Bluetooth Smart technologies to wirelessly transmit data to a head computer, such as a Garmin device, or a cycling app on an iPhone or Android smartphone, such as Strava or MapMyRide. The wireless connectivity also allows Stages Cycling to provide firmware updates for the unit while keeping it sealed to the elements.

The unit uses an accelerometer-based cadence measurement and, because it only measures the power of the left leg, the company doubles the result of the standard equation to give a measurement for the overall power output based on both legs. Stages Cycling says its own internal testing has "found this assumption to be fair, consistent, and work for 99 percent of riders out there."

For those concerned about weight, the StageONE adds 20 grams (0.7 oz) to the bike, which most gram crunchers will agree is nominal, considering the metric it provides. In the scheme of things, it’s roughly half the weight of an energy bar, which many cyclists tuck into the back pocket of a jersey before a ride.

Aimed at road, track, triathlon, cross country, downhill and BMX disciplines, compatible models include the Shimano Dura-Ace 9000; Shimano Dura-Ace 7900/7050; Shimano Ultegra 6700/6750 and Shimano 105 5700/5750; SRAM Rival OCT GXP; Cannondale Hallowgram SI SL; Cannondale Hollowgram SI SL2; Cannondale Hollowgram SL; Shimano XTR M985; Shimano XT M780 and M785; SRAM X9 GXP; SRAM X9 BB30; Shimano Dura-Ace Track 7710; Shimano Saint M820/825 and Shimano DXR MX71.

The base price for the StageONE power meter starts at US$699, and goes up to $950 depending on the crank arm option. While not exactly cheap, Stages Cycling claims its StageONE power meter is "simpler, lighter, and less expensive than any other power meter in the market."

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