Now that we understand the advantages to training and racing with power, (explained in Part 2) it is important to investigate the different types of power meters currently available. A power meter is a considerable investment, so an athlete should select a system that best suits their individual needs. Below are the pros and cons of the the most common power meters currently available, as well as two new systems that likely will become available this year.
SRM (Crank Based Power Meter)
SRM offers a crank based power meter which means that the power is measured is at the crank. SRM was the first company to bring a power meter to market in the late 1980’s and because of this they have the most refined and proven power meters on the market today. There are a wide range of crank options available and the fact that the power is measured at the crank means that you can use them with any wheel set. SRM uses ANT+ to transmit their signal which means that you can use the cycling computer they offer or any other on the market that uses the same ANT+ technology. Crank based power meters can be difficult to change between different bikes (for example from your road to time trial bike), however, if you have compatible cranks it’s not always necessary to remove the entire bottom bracket when switching it over. SRM power meters are also priced higher than other options.
Quark CinQuo (Crank Based Power Meter)
Quarq shipped it’s first power meter in 2008 and was purchased by SRAM in 2011. While the company is relatively new, they are used by some of the top athletes and teams providing a very well made, reliable product. Quarq also offers a crank based system with many different crank set options boasting the same benefits as SRM. Similarly it is vary easy to change wheel sets, however swapping between bikes can be a bit more challenging unless both bikes have the same bottom bracket (in which case swapping can be as little as one bolt). Quarq does not currently offer a cycling computer with the unit but also utilizes ANT+ technology so it is easily paired with your favorite cycling computer. The Quarq CinQo is offered at a slightly better price point than SRM.
CycleOps Power Tap (Hub Based Power Meter)
The CycleOps Power Tap was invented in the 1990’s and purchased by Saris in 2001. Power Tap has become the largest player in the power meter market by offering a large range of power meters at prices that are well below competitors. All Power Tap meters are hub based meaning that power is measured in the hub of the wheel. This allows an athlete to easily swap their power meter between bikes by simply changing out the rear wheel. CycleOps offers arguably the best cycling computer on the market today and also utilizes ANT+ technology which allows you to use your computer of choice. The one downside is that a cyclist must own a separate power meter for each wheel set they plan on using. Many athletes choose to use a back wheel cover so that they are able to train and race on one wheel without any aerodynamic penalty.
iBike Power Meter (Power Estimation Via Sensors)
Rather then using strain gauges like the other systems available, the iBike uses speed data from an ANT+ sensor together with atmospheric pressure, acceleration and wind speed measurements gathered by on board sensors to calculate the power required to overcome the restraining forces of aerodynamic drag, rolling resistance and gravity. The process they use isn’t really power measurement but rather power estimation and is not very accurate. Small changes such as body position affect the iBike’s accuracy. It is much less expensive then other systems on the market and despite it’s claims to be fairly accurate the error associated is too high to make it an effective training tool.
Garmin Vector and Polar/Look Keo Power Pedals (Pedal Based Power Meters)
Both Garmin and Polar/Look have been working very hard to release a power meter that is integrated into the pedals of a bike. Both are claiming that their units will be available in the first Quarter of 2012, however entry into the market on both ends has already been delayed over a year. Although the general public is not able to get their hands on these quite yet, prototypes have shown some advantages. Measuring power at the pedal is very close to the source of where it is generated and pedals are very easily swapped between different bikes. Taking a measurement from each pedal will allow users to look at the force profile of each pedal stroke and report right and left power separately. Polar/Look has announced that their system will only be available for use with polar products (there are currently 3 available) and have not yet released pricing. Garmin will use ANT+ technology so you will be able to use a Garmin or other cycling computer. Garmin’s price point is comparable to other systems currently on the market.
Click Here to Subscribe to Coach Kyle's Blog
Written by Kyle Visin
Santa Barbara Triathlon Club Co-President
USAT Level 1 Coach
Certified CycleOps Power Coach
Co-Founder of KillerTri
A duplicate post is also available at www.killertri.com