If you’ve read my early accounts of running with the Nike+iPod Sport Kit, you’ll know I was extremely pleased with the accuracy of the sensor right out of the box, especially because I was using it with a pair of Saucony Hurricane shoes and not the special Nikes. Since then, I’ve heard from several people who have tried the Sport Kit but aren’t quite as happy with its accuracy, with some reporting it being off by up to 10%. Thankfully, Apple anticipated this problem and has provided a simple fix: Calibration. With proper calibration, the Sport Kit can be just as accurate with your “hacked” shoes as it is with the special Nike+ shoes.
Personally, I think a 10% variation isn’t too bad for a $30 accessory right out of the box, but it can obviously have a huge impact on your workouts, especially if you run long distances. I wouldn’t be too thrilled if the iPod voice was congratulating me for finishing my first marathon if I still had 2.6 miles to run! Since most of the feedback I get is from people who are using their own shoes with some version of my “shoe hack,” I did a little reading on the web and found that even people who are using the Nike+ shoes are experiencing less-than-perfect accuracy out of the box. My (non-scientific) conclusion is that the accuracy of the default calibration has less to do with shoes, and more to do with an individual runner’s stride, running style, foot size, etc. In other words, don’t try to solve an accuracy problem by running out to buy the Nike+ shoes, you may get the same results. Try calibrating first.
Calibrating the Sport Kit is easily done with just a little bit of planning:
1) Find a running track or route where the exact distance has been measured.
This is probably the trickiest step of the process. My usual running route is roughly three miles, which I’ve measured by my car’s odometer to confirm. But because there are several curves and turns, and I typically don’t run down the center of the street, my measurement could be a tenth of a mile off or more. This has never really mattered to me since I just run for fitness, but for calibrating my sensor, it probably wouldn’t do. The best bet for finding an accurately measured distance would be to go to your nearest high-school or college athletic field running track. The standard distance around the inside lane is 400 meters, which is the default distance on the iPod for calibration. If there’s no track accessible to you, check with a local running club to see if they have map of pre-measured routes in your area. If you need to measure a route via your car or bicycle odometer, try to find one that’s a straight line from start to finish. Curves and turns will increase the variation between your car’s path and your running path. Lastly, the Nike+iPod User Guide notes that the accuracy of the kit may vary depending on running surface or incline. So if you generally run on a grassy, hilly route, you should calibrate your sensor under similar conditions… not on a hard, level track.
2) On your iPod, select Nike+iPod > Settings > Sensor > Calibrate.
I found this to be the second trickiest part of the process, only because I expected the Calibrate option to be listed directly on the Settings menu, not one menu deeper. Having switched to Apple computers nearly four ago, I’ve become spoiled in my expectation that everything will work completely intuitively. When an option doesn’t appear on the menu that I expect, it causes me temporary dizziness and disorientation (ok, not really, but it is surprising).
3) When you select Calibrate, this screen appears:
Calibration improves the accuracy of workouts.
By running or walking a known distance at a natural pace you can help Nike+iPod adapt to your workout style and provide the most accurate data.
The next menu offers two choices: Walk and Run.
Choose Walk to calibrate your walking pace.
Choose Run to calibrate your running pace.
Press the center button to continue.
Don’t be shy… press the center button.
4) Select Walk or Run.
The User Guide that comes with the Sport Kit recommends that you calibrate for both, running first, then walking. If you do a combination of running and walking, this is definitely a good idea. If you’re just a runner, it probably doesn’t hurt to calibrate for walking pace as well, but if you’re a walker, there’s probably no need to kill yourself trying to run 400 meters just to calibrate for your running pace.
5) Choose a distance.
The first menu selection is the default distance of 400 meters. This is the standard distance of the inside lane of a running track. The second selection is Custom. Here you can input the number of miles or kilometers of your course starting from .25 miles (.40 km) up to 1.25 miles (2.01 km). I had read somewhere that if you’re a long-distance runner, you should select a longer course for calibration, but I’m guessing that the iPod gets all the info it needs in the first 400 meters.
6) Select your playlist.
After selecting your music, the voice will tell you to press the center button to begin your workout.
7) Press the center button and start running.
Don’t think about the fact that your calibrating your Nike+iPod Kit, just run naturally and comfortably. When you’ve finished the distance, the voice will tell you to press the center button to end your workout. Do it.
8) Press the menu button to finish calibration.
Once you’ve stopped running, press the menu button. At this point, you’ll be told whether the calibration was successful. You can now save the calibration setting, or choose not to and try again.
9) Check the result.
After you’ve saved your calibration settings, try running double the distance and check to see if you get an accurate result. If you’ve just calibrated to 400 meters, try an 800 meter workout. It shouldn’t be off by more than a couple hundredths of a mile (or km).
Lastly, I’d suggest that whether you’re using a “shoe hack” or not, go back and check your calibration every few weeks, especially if you’re training for specific distance or speed goals. The Nike+iPod user Guide mentions that results can vary based on temperature. If you calibrated your kit when it was 90 degrees outside and now it’s 60, it may be a good idea to do it again.
The Nike+iPod Sport Kit will never be perfectly accurate under every condition, but by following these simple calibration tips you’re likely to have the most accurate results possible… whether you’re using the Nike+ shoes or not.
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