POWER METERS 1 de 6 - SRM

 

 

There are two prerequisites to successfully adopt a power centric training philosophy: the time required to understand, interpret and ultimately benefit from all of the data that will be seen and collected; and the non-trivial investment in a power meter. Here we outline the competing units and collate links to a number of independent product reviews.

SRM Quarg PowerTap Power2Max Garmin (MetriGear) Vector Polar/Look Keo Power Pedals Others

The SRM is the longest living, most proven, highest profile device, the gold standard in cycling power meters. First developed around 20 years ago it was adopted by elite cyclists as early as 1988, including the innovative Greg Lemond & "The Doctor" Chris Boardman. Knowledgeable coaches suggest it is the least prone to failure meaning it will last a very long time, plus it can be recalibrated using a simple procedure, as often as you like. The head unit is a fine example of industrial engineering, compact and robust, it fits very securely offering all of the computer functionality that a racing cyclist needs and none of the extras he doesnt.

Appearance
Manufacturers Site	www.srm.de
Data Measured	Speed, cadence, HR, power, ride time. Max and average (as applicable). Intervals. Kilojoules energy spend. Later models have a barometric altimeter supporting total ascent.
Variants	Normally bought intetrated with your preferred crankset, inc. dura ace, FSA, Sram also in compact variants with the expected choices of crank arm lengths.
Power Unit	Integrated into a special chainset spider. 8 strain guages. (20 in a unique "science" version!)
Head Unit	Wired versions work with the Powercontrol V, newer wireless versions with the Powercontrol VI, 7 or any ANT+ compatible device.
Installation	Replacing a modern crankset is fast and easy requiring no special tools, plus the head unit is easy to fit onto any standard size handlebars. The unit requires a sensor fitted a few millimetres from the crank spider, either underneath the bottom bracket housing or on a seat stay. There are a few options here depending on frame design: a rubber band (supplied), zipp ties, an adapter on the cable guides, or silicone, not a problem. Wired versions require a bit of tactical cable routing but again this is not difficult
Software	SRMWin is included with the device, this will always be the software of choice to configure the head unit, and allows simple ride analysis. As with all manufacturers software it is not as rich as some of the dedicated analyis packages such as TrainingPeaks & Golden Cheetah which would be a recommended extra.
Reliability	SRM's have an exceptional reputation for reliability. The crank spider may need a battery change after a couple of years usage and it's advisable to have this done by a dealer if not SRM in Germany which probably incurs 2-way shipping costs. The head unit battery will also need replacing by a dealer when it stops holding it's charge, unlikely inside 2 years. Some care is required not to break the connection wires in the wired variant. We have seen reports of water ingres to the cranks in earlier models but this is not recognised as a common issue.
Price	The gold standard power meter rightly commands a gold standard price of £2900 for the Dura Ace "professional" system including the head unit. You can save £250 by purchasing just the base unit and adopting a Garmin Edge 500 computer instead of SRM's own PowerControl. Keep in mind that the package you are buying includes a high end chainset, heart rate monitor and computer so you can discount the price of all these things or at least the value of selling what you have from the price, e.g. £300 for the Dura Ace 7900 chainset.
Service	SRM has service centres at the factory in Germany, in the US and in the UK, all are noted for efficiency and quick turnaround. Tip:keep the box that your crank came in, it it will come in handy when the time comes to courier despatch your beloved SRM for service.
Accuracy	Most cranksets incorporate the "Professional" unit with 8 strtain guages, accuracy is +/- 2% assuming good calibration and setting of the "zero-offset" before every ride.
Calibration	Can be done by the manufacturer in conjunction with a battery change, or by any knowledgeable person inluding yourself. See 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 Dura Ace 7900 chainset integrating the SRM spider weights just 80 grams more than the standard Dura Ace 7900 chainset.
Who uses one?	Countless professional riders. At the time of writing SRM list 9 Pro-Tour teams using SRM's.   http://www.cyclingpowerlab.com/Introduction.aspx