Being a coach and bike fitter, I get lots of questions from my athletes about training with power, and technical questions about which power meters are best for them. Without going into obsessive detail over the many options available, I have compiled a simple guide that will help to explain your choices.
|Garmin Vector 2||Pedal based||both||179 g/pedal||900/1500|
|Powertap P1 pedals||pedal based||dual||398 g total||1200|
|Powertap G3 Hub||Rear wheel hub||single||325 g||790|
|Rotor Power Crank||Crank arm based||dual||30 g + crankset||1594 (plus rings)|
|Rotor Inpower||Crank axle based||single||55 g + crankset||1079|
|Quarq Elsa RS||Crank spider based||dual||138 g + crankset||1399 (plus rings)|
|Stages Power Meter||Crank arm based||single||20g g + crank arm||700-900|
|Pioneer Power Meter||Crank arm based||dual||66 g + crankset||1000-1850|
|iBike Newton||Bike computer||single||?||499|
|SRM power meter||Crank arm based||dual||136 g + crankset||2970|
Now we need a bit of explanation. There are 3 major different types of power meters based on their location on your bike: mounted in a set (or single) pedal, mounted on/in your crankset, mounted in the hub of your rear wheel. There is one exception to this rule (iBike Newton) which calculates power from a special bike computer mounted on your handlebars. All of the units listed (except for the iBike will pair up with any Garmin bike computer that receives power data).
Some power meters measure power from one leg, some measure from both legs. The dual legged power meters are a bit more accurate, but it is not yet clear to me (as a coach) whether they produce any better training results. If you have a significant leg strength imbalance, then the dual sided power meters will help you to observe, and potentially correct, that issue. I have found that most of my athletes fall within a range of 2-4% difference between right/left leg output. If it’s more than that, then either your bike fit, or your physiology needs some correction.
The weight of modern power meters are relatively low, aside from the Powertap hub, which is 325 grams. However, if you subtract the weight of a typical rear wheel hub (range is from 200-400 grams), you can see it doesn’t add much more than any of the other power solutions. Same goes for the pedals, which are (for the Vector pedals) 179 grams/pedal including the weight of the cleats. However, a regular set of Look Keo pedals (upon which the Vectors are based) are only 173 grams including cleats. So, the additional weight of a power meter is generally not much of a determining factor unless you are a gram counter.
Pricing is also a bit complicated based upon whether the power meter comes with chainrings or not (for example, the Rotor power crank is $1594, but you need to buy chainrings which can add up to $300 on top of that). Also, the type of crankset or crankarm you buy will determine price (for example, a Stages Shimano 105 crankarm is $700, a Dura Ace crankarm is $900…..both including the power meter). To keep it really simple, the prices range from the Newton at $500 up to the SRM at nearly $3000.
All of the powermeters, except for the iBike, measure power directly based on the force you produce on the bike. The iBike takes a very different approach in that it calculates power indirectly based on a variety of physical forces, including: weight of you and the bike, wind speed, hill slope, etc. It’s basically a physics engine installed in a cycling computer.
I have personally used almost all of the power meters I’ve listed here except for the SRM and the two pedal based power meters. However, aside from the brand new Powertap pedals, my athletes have used all of the equipment listed above. My take away is this: if you wish to get into the power market as inexpensively as possible, get one of the single sided power meters. The Stages units are particularly attractive as they are relatively inexpensive, incredibly light and their firmware is continually being developed to create worthwhile upgrades. If you wish to opt for a dual sided power meter, I am currently drawn to both the Rotor and Pioneers power meters. The Rotors feel incredibly strong, are lightweight, and are designed to use the exceptional Rotor Q rings (ovalized chainrings; the benefits of which will have to wait for another article). The Pioneer has some great measurement features (for example, measuring pedal vector forces and actual amount of wattage generated in each leg), but you have to purchase one of their own head units (about $300) to see all of the data these meters can measure.
If you wish to get a specific recommendation for which power meter will work best for you, please feel free to contact me and I’ll be happy to help out. Encina will be able to obtain any of these products for you and provide installation as well.
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