Power meters are a powerful tool. While there are a growing number of companies offering models that have caught our eye, only a select few are, in our estimation, worthy of your consideration.
There are a few different methods by which the various power meters measure torque, and thereby calculate your power. Strain gauges, strips of wire that when flexed change in their conductivity, are mounted either in cranks, bottom brackets, hubs, or on a trainer unit. While trainer mounted units offer fantastic utility, you will be limited to data compiled during your indoor sessions. Bottom bracket mounted units have had reliability issues in the past. When it comes to all around performance, two makes of power meters have consistently risen above the rest: PowerTap and SRM. Which unit might be right for you? Read on...
We've used both of these industry driving units and they are both excellent options. But both have limitations that one ought to consider when deciding between them. One important question to ask yourself is if you are going to race with power, or limit your measurement to training sessions. We find that some of the best data that you will compile is from racing. Want to see what your power output was just before the group dropped you in your last road race? Want to see how much effort you were exerting in the last 2 laps of the local crit? Need to calculate your LT based off of your results at the state TT champs? Racing with a power meter is an easy way to do all of these things and more. However, some prefer to not be tied to a constantly fluctuating number while they are racing, instead going on feel. No one wants every aspect of their racing to be dictated by their power meter.
The PowerTap is a hub mounted unit. The strain gauges are enclosed into the hub, which is then built into the spokes and rim of your choosing. This makes the unit extremely easy to transfer between bicycles, especially the newer wireless incarnations of the PowerTap. In fact, it is literally as easy as changing a wheel! For athletes who own and train on more than one bicycle, this unit is a pleasure to switch between bikes. The disadvantage to this design is that you are limited to one wheel, a factor to consider if you own and use multiple sets of wheels for different racing and training situation. For example, if you already own a set of super-fast Zipp 808's, you'll have to either have a PT hub built into your 808, and then train and race on it, or purchase an additional hub to have built into a training wheel. The PowerTap displays 3 data meausrements at a glance, and while you can scroll through the current, average, or maximum of any value, you can only scroll through one value at a time.
This brings us to the other excellent powermeter option, the SRM. To be short, the disadvantage of the SRM is the price: $3000 for the basic cranks and closer to $4000 for the Dura Ace or FSA models (which also happen to have 8 strain gauges versus four in the basic model). The SRM has the reputation for being the most reliable unit once the initial setup and installation is completed. We say once the setup is completed because, in our experience, there is almost always some tweaking (for lack of a better word) that needs to be done in order to get the unit functioning (be it adding magnets to the crank sensor, or re-installing USB-driver software to get the download cable to be recognized). It's never very difficult and does not take much time, but on a $4000+ unit it would be nice to not have any hiccups. The SRM displays quite a bit of data at a glance: it has 4 constantly displayed measurements (Power, HR, Speed, Cadence) and a 5th measurement scrolls through time, distance, and altitude. Pressing the mode button shifts each of the 4 main measurements to averages, and another click of the mode button takes the user to the maximum of each measurement. Data is very easy to access on the SRM. The other advantage that the SRM has is that, because it is a crank-based unit, you are free to use whatever wheels you choose. This might make the cost of the unit much more reasonable if you intend to use multiple rear wheels.
The wonderful world of power meter training can be confusing and difficult to navigate at the outset. Feel free to give a call or stop by the studio and the CMS staff will be happy to assist you with these powerful tools!
