For the uninitiated, power meters have become increasingly popular by serious cyclist for effectively and efficiently tracking performance. They usually take the form of a swappable hub or crankset installed on your bike which transmits information to an on-bike computer. Though I’ve only used them in a very limited capacity, they’re a ridiculously great way to track your performance. The only real downside to this type of solution is that they can cost an arm and a leg (~$800 – $2,000) and are therefore a little inaccessible to average blokes like me.
For those curious as to the benefits of training with a power meter Wikipedia does a good job at summing things up:
Power meters provide instant feedback to the rider about their performance and measure their actual output; heart rate monitors measure the physiological effect of effort and therefore ramp up more slowly. Thus, an athlete performing “interval” training while using a power meter can instantly see that they are producing 300 watts, for example, instead of waiting for their heart rate to climb to a certain point. In addition, power meters measure the force that moves the bike forward multiplied by the velocity, which is the desired goal. This has two significant advantages over heart rate monitors: 1) An athlete’s heart rate may remain constant over the training period, yet their power output is declining, which they cannot detect with a heart rate monitor; 2) While an athlete who is not rested or not feeling entirely well may train at their normal heart rate, they are unlikely to be producing their normal power—a heart rate monitor will not reveal this, but a power meter will. Finally, power meters enable rider to experiment with cadence and evaluate its effect relative to speed and heart rate.
When I ran across iBike the other day I thought it seemed like a pretty solid alternative for those a little more limited in the pocketbook so I decided to investigate things further. For $199 you essentially get a power meter-esque tool, that doesn’t require you to change or swap any of the parts on your bike. The iBike isn’t a “true” power meter however – where power meters measure the amount of force you’re outputting, the iBike measures the amount of force acting upon you (ie. drag) and then uses that to calculate your output. Apparently after a slightly finicky initial calibration, you’re pretty much set.
Effectively the way the iBike works is to measure your aerodynamic drag coefficient and rolling resistance through a number of ‘ramp’ tests which it uses along with wind speed, speed and acceleration to calculate the power the rider is applying – Essentially measuring your power output indirectly.
Now before you go rush out and buy one I dug a little deeper, and there are a few drawbacks, mainly a result of it’s indirect measure of power:
- Power reading doesn’t change with your riding position (ie. if you stand and mash on the pedals), the reading will only change if the change in riding position results in a change of inputs (ie. increase in speed, accommodating for a headwind, etc.). In light of this, the iBike would probably be a ridiculous choice for a mountain bike.
- Power readings tend to be more of an average reading of power outputs rather than a real-time detailed recording (as per above)
- Won’t work on a trainer (since you need air resistance to get a reading)
Though, there are some definite benefits over traditional power meters as well:
- Much lighter – only 60g
- No ‘install’ necessary
- Includes an altimeter and inclinometer
- Optional cadence unit as well
- Syncs up with your computer
- Higher models can do everything wirelessly
- Way cheaper
Generally, I think the age old adage still holds true… You get what you pay for. For somebody interested in tracking their training getting a little more insight into their performance and is somewhere where you’re not sitting on a trainer for half the year, the iBike might be a great fit that’ll save you a ton of cash, but if you’re interested in the minute details of your performance start saving for a ‘classic’ power meter, or for those that think that they can adequately manage their performance through other means (ie. heart rate) then save your money.
After a couple of great clarifications by John Hamann of iBike I thought it important to pull in the comparative data he is referencing directly – From the graph below, it’s pretty tough to tell the difference between the three power meters despite varied elevations and speeds. You can view a full analysis here.
Judging from this data, as well as the optional ‘firmware key’ that accounts for rides on the trainer, the cons I’ve highlighted above definitely do not hold as much water – placing the iBike as an even more serious contender.
I also wanted to highlight that the software come in both Mac & PC platforms – as a Mac user this is something I genuinely appreciate.