Sunday, October 4, 2009

Nike+ iPod Sensor review

My serious running friends have fancy GPS watches. I was envious of their ability to just step out the front door and run in any direction, knowing they could track their distance and adjust the route as needed to meet a desired goal mileage. My method previously required driving a car and measuring different routes in advance with my odometer. It was time-consuming and involved a lot of trial and error to get the right route for a chosen distance to end up back at home or wherever I might park my car to run.

Then I learned about a website called, and realized that I didn't need any fancy equipment to plan my routes. On the website I can simply click my starting point, and click, click, click along the roads on a map. If my unfinished loop isn't going to end up long enough, or is getting too far from home base for my desired distance, I just hit undo a few clicks and add or remove streets as needed. This serves my purpose, and although it doesn't allow the same flexibility as GPS perhaps, it is absolutely free. I just have to spend a few extra minutes planning a route and then committing the important turns to memory before heading out. I also like the ability to email proposed maps to my running buddies, and is especially helpful when I'll be meeting somebody partway through my run because we have different distance goals for the day.

So the distance problem was satisfactorily solved for me on But another very useful feature of the GPS tool is real-time pace tracking. The only way for me to know how fast I run is to do a little math at the very end of my workout: speed = distance / time. I feel that I have reached the point in my training that I am ready to work on increasing my speed and maintaining a more constant pace throughout my runs. In order to do that, I need to know how fast I am going at various points on my course, not just the average at the end.

A new Garmin watch wasn't going to be in the cards for me, that I knew. But a while ago I searched for used models on craigslist and eBay. I couldn't justify buying one of the ancient models when I have heard the technology has been significantly improved over the last few years, but the previously-owned newish models were still out of my budget. And so I accepted that I would do without.

Over the summer, while shopping for a new pair of running shoes at the Nike Factory Store, I noticed most of the shoeboxes were labeled with the Nike+ logo. I had heard of it, but read more information on a little brochure explaining that a Nike+ shoe can talk to your iPod wirelessly with every step, and tell you your time, distance, pace, and calories burned while you run. Bingo.

It didn't take me long to figure out that the shoes are simply Nike+ ready, meaning there is a little compartment in the shoe for the sensor, which would have to be purchased separately. The Nike Plus Sensor sells online for under $30--about a tenth of the price of a Garmin.

At such a small pricetag, the question became not whether I could afford it, but whether it would be worth it. Would it be accurate enough to be useful? For that cheap, there was definitely no GPS technology inside. I searched online for more information about how exactly the Nike+ iPod sensor works, but found very little besides where to buy it. Even the instruction manual pdf did not provide any clues to how the sensor measures distance and pace, or what amount of accuracy should be expected.

I decided to buy one and give it a try. And since I found the internet to be slightly lacking helpful information on this product, I hope that my review will be helpful to some curious shoppers out there.

What is Nike+ iPod sensor?
Essentially the Nike+ sensor is just a pedometer. It tracks your steps. But unlike the cheap little pendulum clip you can attach to the front of your pants, the Nike+ can do instantaneous calculations based on the number of steps you take over measured time intervals to determine your current pace. There is also some calculation for calories burned, and of course it times your workout as well. All of this information is displayed on your iPod screen and can even be received through instant audio feedback on your earphones.

How accurately does Nike+ measure distance?
The sensor comes ready to use out of the box and claims to be "accurate for most runners," but I would highly recommend calibrating it immediately. You simply run an accurately measured distance in the calibration mode (for example 400 meters, one lap around a standard track on the inside lane) and then the sensor (I assume) determines your average stride length.

You can also calibrate the sensor after having completed a run with a known distance, which is a nice feature. I ran with my new, uncalibrated Nike+ sensor alongside a friend with GPS, and mine was pretty far off of her distance measurement. After the run, I simply input the # of miles we had just completed, and it calibrated for future runs. Since then, my Nike+ has provided measurements that are within a tenth of a mile of my Garmin friends'. I also look at the mile-markers on before leaving home, and often my Nike+ gives me the mile count within a driveway-length of the satellite map's.

I propose that the longer the run, and the more hills involved (especially if up- and downhill lengths are disproportionate), the less accurate the distance will be. Generally, your stride will be longer going down hill and shorter going up hill, and as far as I can conclude, the Nike+ doesn't have a way to account for these differences. If you go up and down hills fairly evenly, it would probably balance out. Today I planned a 12-mile route on the map website, and when I reached the end of the route, my Nike+ sensor had measured 12.25 miles. That is the most discrepancy I have ever noticed, but my friend also reminded me that those online maps may not be 100% accurate either.

How accurately does Nike+ measure pace?
The answer to this question echoes the previous one. Since the Nike+ sensor determines your average stride length through calibration and then counts the # of steps you take over measured time intervals, its accuracy depends on your stride length remaining constant. Hills, very long runs where you might significantly shorten your stride will impact the pace measurement (as well as distance). For the casual runner, the difference is probably not enough to be concerned about. I also am not sure how long it takes for the sensor to calculate and communicate with the iPod receiver. I would like to know if the lag time is 3 seconds or 10 seconds or 1 second. Overall, for me, the pace reported is close enough. After all, I could previously only venture a guess at my speed without spending $300 on a Garmin.

How does Nike+ interact with the iPod?
Nike+ iPod is supported on all iPod nano models, iPod touch (2nd gen), and iPhone 3G S. So make sure you have one of those. I have an iPod nano 2nd generation, so that's the only model on which I can comment specifically, but the features should be more or less the same on all (and the manual covers the differences in detail).

All of your workout information is displayed on the screen, and you can still control your music throughout. You can choose a male or female voice to give you periodic updates on your distance (or turn the voice off), and press the center button at any time to hear your time, distance, pace and calories. I suppose this is nice if you don't want to have to look at the screen.

I use an arm band for my iPod, and my biggest complaint about the entire system is that it's difficult to read the screen on my arm because the information is upside-down. I would strap the iPod on in an inverted position, except that the case is open on the top, so it would just fall out. Perhaps there is an armband case that is secure on the top so I could wear it upside-down. Hm. I'll have to look into that. Also it is tedious to have to tap the touch pad every time I want an update, as I can't read the screen in motion without the backlight.

Another cool feature is the ability to choose a power song. When in need of some extra motivation, you can hold down the center button and your special song starts a-pumpin'. I haven't actually used that feature yet, but it seems fun.

The iPod interface for Nike Plus also allows you to:
  • choose distance, time, or calorie goals for your workout, or just start going.
  • listen to any playlist or all songs, or no music. You can receive calls on the iPhone and your workout will automatically be paused.
  • review previous workout summaries
  • send your workouts to
  • create custom workout shortcuts (this is a useful feature I need to start using!)
  • link one iPod receiver to multiple sensors.
What if I don't have Nike+ shoes?
Aha! Nike wants you to think you need those, but it's a trick. I actually saw some poor schmuck selling his sensor on eBay because he realized his shoes aren't compatible with it. Yes, the Nike+ shoes have a foam pad under the foot bed which can be removed and replaced with the Nike+ sensor. Yes that keeps it all neat and tidy and out of your way. But I came across dozens of various sensor "pods" that you can buy for under ten bucks and attach to any shoe. These little pouches hold the sensor and attach to your laces it seems. So you don't need special shoes, but without them you'll need a little pod for the sensor.

How does Nike+ measure steps taken?
I actually don't know the answer to this. Maybe nobody cares, as long as it works. But I am curious. Since the sensor does not need to be under the footbed (see above), the pedometer must not measure steps through impact, so perhaps it is a pendulum effect similar to the cheap hip-clip models. Before I got my own Nike+ sensor and realized that indeed it is just a fancy pedometer, I wondered if there were TWO sensors--one for each foot--which could somehow communicate with one another. If that were the case, distance and time could be very accurate, if the two sensors could measure their distance apart and when they cross each other...I'm no engineer though, and maybe that technology is just in my imagination...thus far. It might use impact, however, without requiring the full weight of the body. Just the impact of foot strike is probably enough to mark a step taken.

Overall, I am very happy that I tried the Nike+ Plus iPod sensor. In my experience Nike+ has delivered surprisingly accurate information; undoubtedly better than no information. For under 30 dollars, it is certainly worth the investment.

This review is based solely on my own personal use of Nike+ and my related opinions. I don't work for Nike or Apple and apologize for any misrepresentations that may unknowingly exist. Hopefully this report provides additional insight to shoppers looking for more information about this product.


Bridget said...

What a thoughtful review. I am glad to read it - I've been wondering about this product. I only wish it could somehow work with my Shuffle. I realize that the display of stats is a major component of the whole idea, but there must be a way...

Anonymous said...
This comment has been removed by a blog administrator.
go0ri said...

Thanks for the nice Review.

Monette said...

This is exactly the kind of review I needed. Off to find a pod and buy a sensor. Thank you.

Derek said...

Very helpful! Thank you for taking the time to write such a nice review... I'd like to start running and was interested in all this + business. You answered my questions.

George Wells George Wells said...

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