POWER METER - 2 de 6 - QUARQ

For several years the choice between power meters amounted to the crank based SRM or the rear hub based PowerTap. Since the SRM has always been the gold standard power meter one can imagine the excitement that came with the launch of a second crank based system, moreso when the device made it's way into the professional peloton via the Cervelo Test Team. A couple of years later, in terms of accuracy and reliability, the Quarg has earned a reputation somewhere between the SRM and the PowerTap but gains with some nice features. Unlike the SRM the user can easily perform a battery change and unlike the PowerTap this is a unit you can recalibrate at home (with a simple iPhone app, Qalvin). Despite early promise there is, as yet, no Quarg head unit billed "Qranium" so the wirelessly transmitted power data would typically be be viewed with a Garmin computer however we expect this device to continue bulding a great following.

Appearance
Manufacturers Site	www.quarg.com
Data Measured	Speed, cadence, HR, power, ride time. Max and average (as applicable). Kilojoules energy spend.
Variants	Normally bought intetrated with your preferred crankset, inc. FSA & SRAM however SRAM acquired Quarg in May 2011 so future choice may be restricted. Compact variants are available.
Power Unit	Integrated into a special chainset spider. 10 strain guages.
Head Unit	At the time of writing there is no dedicated head unit (Qranium) from Quarg. Any ANT+ compatible computer will suit such as the Garmin Edge 500 (pictured).
Installation	Replacing a modern crankset is fast and easy requiring no special tools. The Quarg measures cadence using a super-strong rare earth magnet that can be sited on the chainstay upto 12mm from the inside of the chainset using expoxy putty.
Software	There is no proprietary analysis software from Quarg necessitating a separate purchase of TrainingPeaks WKO+.
Reliability	We have not seen complaints regarding the longevity of Quarg units. We have seen some reports of power spikes (generally caused when the product of torque x cadence leads to a spurious number) and dropouts ocurring in power data from the Quarg and suggestions that the torque applied to chainring bolts can affect the accuracy/consistency of power readings. There is an obvious fix for the latter - a torque wrench + recalibration.
Price	A Quarg integrated into an FSA SL-K Light chainset retails for £1650. Add £200 for a Garmin Edge 500 and £80 for a copy of WKO+ for an "on the road price" of £1920.
Service	The Quarg factory is located in South Dakota, USA. it is unclear if any of the "rest of world" dealers can act as service centres.
Accuracy	Claimed accuracy is +/- 2% assuming good calibration and setting of the "zero-offset" before every ride. There is an option to specify "auto zero".
Calibration	Can be done by the manufacturer, or by any knowledgeable having access to the "Qalvin" iPhone app, including yourself. You can check the calibration with our Power Meter Calibration Calculators There is no need to open the unit or remove it from the bike for calibration.
Weight Penalty	As an example the FSA SL-K Light integrated version weighs 808 grams versus the standard SL-K Light chainset at 580 grams. Penalty 228 grams.
Who uses one?	The Cervelo Test Team used Quarg.
Top Reviews	Pez Cycling News Velonews Competitive Cyclist Flamme Rouge

The PowerTap has been around since the the turn of the century, appealing due to a significantly lower pricepoint than the SRM and to those riders who prefer the idea of a wheel rather than crank based device. PowerTaps have been adopted by a number of professional cyclists, most visibly making their way into the professional peloton via Garmin Chipotle, and continue to enjoy a significant following. This isn't a system that can be calibrated in the field, we also hear of a few more issue viz-a-viz reliability and longevity (in fairness we compare to the gold standard SRM), but let's be clear - it does the job of accurately measuring power and gets you up and running with power and without breaking the bank.

Appearance
Manufacturers Site	www.cyclops.com
Data Measured	Speed, cadence, HR, power, ride time. Max and average (as applicable). Kilojoules energy spend.
Variants	Several units having different weights and price points, upto the lightest G3C featuring ceramic bearings. Bought either as a stand-alone hub for building into your preferred wheelset (with a choice of hole counts) or integrated into a wheel set.
Power Unit	Integrated into a rear hub. 8 strain guages. Integrated cadence detection.
Head Unit	Compatible with ANT+ computers. Cyclops themselves make and recommend the Joule 2.0 computer. A Joule 1.0 (smaller, better for racers) and Joule 3.0 (larger) also exist.
Installation	Assuming the rider takes delivery of a ready built wheel installation is as simple as swapping this in to the desired bike.
Software	Cyclops supply PowerTap units with their proprietary "PowerAgent" software. Many users have purchased WKO+
Reliability	We have seen more reports of failed PowerTaps than any other power meter. It seems there comes a point in the life of every PowerTap when the "torque band" fails, the power readings become notably unrealistic, and a return-to-factory service is required.
Price	The PowerTap G3 hub costs £975. Add wheelbuilding or purchase with a basic alloy wheelset for circa £1125. Add a pricey £360 for a Joule 2.0 head unit, £165 for the Joule 1.0 or £200 for a Garmin Edge 500. Minimum "on the road price" for a G3 is therefore £1140.
Service	We have read reports of fast, efficient service whenver a unit needed recalibration or repair.
Accuracy	Claimed accuracy is +/- 2% assuming good calibration (at the factory only) and setting of the "zero-offset" before every ride. There is an "auto zero" function.
Calibration	Not a DIY procedure, requires return to a service centre. See our Power Meter Calibration Calculators for the "stomp" test which is a gross error check.
Weight Penalty	The G3 hub, the lightest of the range, weights in at 325 grams. A Dura Ace 7900 rear hub weighs 254 grams. A weight penalty of 71 grams is impressive.
Who uses one?	The PowerTap was most conspicuous in the professional peloton as an accessory of the Garmin Chipotle team.
Top Reviews	Cyclops (Review Links) Robert Chung (accuracy tests) Bertucci et. al (accuracy versus SRM)

As with the SRM & Quarg the Power2Max is a crank based power meter however this one comes with a significant difference - price. Assuming you buy a Power2Max integrated into a Rotor 3D+ crank, possibly the most popular and aesthetically pleasing of several options, this system will set you back just £1000. Add around £100 for some chainrings (not supplied), around £200 for a Garmin Edge computer, and you can enjoy the benefits of power for a price that comes close to that of a G3 PowerTap. The Power2Max hasn't been around for long and comes from a relatively anonymous German company (doesnt so much great engineering?) but early reviews suggest this system lacks little in terms of build quality, accuracy or reliability. Given the limitations of hub based power measuring technologies such as the PowerTap (loss of freedom over wheel choice and the smaller matter of power loss in the drivetrain) we feel this device represents a serious option at it's price point.

Appearance
Manufacturers Site	www.power2max.de
Data Measured	Speed, cadence, HR, power, ride time. Max and average (as applicable). Kilojoules energy spend.
Variants	Available as a stand-alone chainset spider from EUR 690 but most will purchase a unit ready-integrated into one of several possible chainsets.
Power Unit	Integrated into a special chainset spider. 4 strain guages.
Head Unit	At the time of writing there is no dedicated head unit. Any ANT+ compatible computer will suit such as the Garmin Edge 500 (pictured).
Installation	Replacing a modern crankset is fast and easy requiring no special tools however note that the Power2max is generally supplied without chainrings so you will need to fit these. The Power2max measures cadence via an innovative on board accelerometer so there is no magnet to site as with the SRM & Quarg.
Software	There is no proprietary analysis software from Quarg necessitating a separate purchase of TrainingPeaks WKO+.
Reliability	The first units began shipping in 2011 so there is not much of a track record to comment on here. The comments we have seen indicate, so far, consistent and reliable power numbers.
Price	Integrated into a Rotor 3D+ crank you will pay £1000, plus circa £100 for chainrings. Add £200 for a Garmin Edge 500 computer (pictured) and £80 for WKO+ and the "on the road" price is £1380.
Service	Contact the supplier.
Accuracy	Claimed accuracy is +/- 2% assuming good calibration and setting of the "zero-offset" before every ride. This unit has an auto-zero capability which cannot be disabled - some users have expressed concern about risks to accuracy.
Calibration	At the time of writing we understand the field/user calibration is not possible.
Weight Penalty	A Power2max spider compatibible with the Rotor 3D+ chainset weights 470 grams compared to the original spider at 264 grams. Weight penalty 206 grams.
Who uses one?	The manufactuers website reports thant Susanne Buckenlei won the Norseman 2011 with a Power2max.
Top Reviews	Steve Irwin

Available from March 2012 this has been a much anticipated device developed initially by MetriGear who were then acquired by Garmin. Clearly Garmin is a respected name with a formiddable product portfilio reaching way beyond the cycling domain so expecations of the Vector are high. As with the Polar/Look Keo Power Pedals, assuming the accuracy and durability doesn't disappoint, what is not to like about an easy-to-fit, easy-to-switch power metering device that comes with a truly trivial weight penalty and a keen price tag? We will link comprehensive reviews when available.

Appearance
Manufacturers Site	www.garmin.com/vector
Data Measured	Speed, cadence, HR, power, ride time. Max and average (as applicable). Kilojoules energy spend. Left-Right power balance.
Variants	N/A
Power Unit	Integrated into pedal axles. Data is sent to the (silver) transmitter units and onwards to the head unit with ANT+
Head Unit	In theory any ANT+ compatible head unit will suit but as a Garmin product the obvious choice of head unit is the Garmin Edge.
Installation	Very easy! Use a hex key to change your pedals then configure your crank length and pair to the head unit.
Software	TBC
Reliability	TBC
Price	The indicated launch price is £1149. Add £200 for a Garmin Edge 500 head unit and £80 for WKO+. This is a keen "on the road price" £1429.
Service	TBC
Accuracy	An accuracy of +/-2% has been indicated.
Calibration	Procedure TBC
Weight Penalty	A good pair of Look Keo pedals (the "Keo2Max Carbon") weighs in at 328 grams including cleats and screws. The Vector pedals are claimed to weigh 356 grams including the transmitter pods and cleats. Weight penalty 28 grams which appears to make this the least weight-penalty power meter!
Who uses one?	We understand that Garmin-Cervelo will be adopting the Vector in the winter of 2011/12.
Top Reviews	DC Rainmaker

Polar's first attempt at power measuring technology, a chainstay based chain tension sensor released several years ago, looked like a dogs dinner and unfortunately, without a lot of attention or luck, the data it delivered had a tendency to look much the same. The product of this collaboration with the worlds leading road pedal manufacturer looks altogether more promising. As with the Garmin Vector, assuming the accuracy and durability doesn't disappoint, what is not to like about an easy-to-fit, easy-to-switch power metering device that comes with a minimal weight penalty and a keen price tag? Possibly just one thing - this device communicates only with Polar head units using a Polar proprietaty protocol distinct from ANT+. The first of these devices is shipping at the time of writing so we look forward to sharing comprehensive reviews in due course.

Appearance
Manufacturers Site	www.lookcycle.com
Data Measured	Speed, cadence, HR, power, ride time. Max and average (as applicable). Kilojoules energy spend. Left-Right balance.
Variants	N/A. Perhaps there will eventually be a version with Titanium axles as is the trend with Look pedals.
Power Unit	Integrated into pedal axles. 8 strain guages per axle. Force and cadence data is sent to the transmitter units and onwards to the head unit with a Polar proprietary protocol W.I.N.D. (i.e. this unit stands out as not ANT+ compatible).
Head Unit	Choose from the Polar CS500, CS600 or CS600X computer.
Installation	Very easy! Use a hex key to change your pedals then configure your crank length and pair to the head unit.
Software	Supplied with Polar ProTrainer software. WKO+ is also compatible with Polar files.
Reliability	TBC
Price	£1500 or £1700 with a Polar CS600 computer.
Service	TBC
Accuracy	Claimed accuracy +/-2%
Calibration	Procedure TBC
Weight Penalty	A good pair of Look Keo pedals (the "Keo2Max Carbon") weighs in at 328 grams including cleats and screws. The Keo Power pedals weigh 405 grams including the transmitter pods and cleats. Weight penalty 77 grams.
Who uses one?	The Cofidis team were involved in testing. We expect to see this device entering the peloton via the many Look &/or Polar sponsored teams.
Top Reviews	Polar promotional Video Look Promotional Videos

Brim Brothers Zone

Manufacturers Site: www.brimbrothers.com

The Brim Brothers Zone is a "forthcoming" device that may become the first cleat based power meter. The thinking goes that power is specific to a rider, not a bike, so why not have the cyclist wear the power measuring device in his cleats / on his shoes, then it transfers easily to whatever bike he may want to ride in a way that crank, hub or pedal based devices cannot. At the time of writing we have seen pictures of prototype devices but little else. We wish them well in delivering this product to market.

iBike

Manufacturers Site: www.ibikesports.com

The IBike device does not directly measure power output, instead it estimates power by attempting to capture all of the forces the cyclist may be experiencing (gravity, via climb), (air resistance, via an inbuilt wind speed sensor...greatly dependent on your CdA), (rolling resistance, via speed) and (acceleration, via an inbuilt accelerometer). If you beleive in the laws of physics (at Cycling Power Models we most certainly do), if you beleive in your ability to calibrate the device accurately and you beleive in some of the assumptions it may make (not so easy) then your only remaining concern would be the kinds of measurement errors that might plague this device. The iBike has been around since 2006 but it has not achieved a significant following.

Ergomo

Manufacturers Site: www.ergomousa.com

The Ergomo has experienced a chequered past. Originally launched in 2003, relaunched in 2005, and again in 2010, the companies history has been punctuated by technical problems with the product leading to cessation of trading and even bankruptcy. The device itself is effectively a bottom bracket that measures power at the left crank, and then doubles it. Obvious issues are the maturing trend away from separate crank and bottom bracket intallations (eg Shimano Hollowtech), the history of technical problems (including but not limited to water ingress at what is the lowest point in any bike frame), and the reality that not everybodies power output is twice the left hand side. This is perhaps a shame, the Ergomo gained some popularity for a sophisticated head unit, Triathlon Choice magazine voting it "most innovative product" in 2008, but we feel it would be a brave eccentric who would invest in the latest incarnation of the system.