Convert Nordictrack revolutions to miles

!!d5t(HwBGM~$(KGrHqQOKjoEq4+Z!DEtBKy6!R3G!w~~_32We recently purchased a Nordictrack elliptical trainer.  The machine is pretty nice, but both my wife and I immediately noticed a major annoyance: there wasn’t any documentation about how many “miles” the elliptical travels over the course of a workout.  We’re both accustomed to that form of measurement; the number of revolutions per workout was essentially meaningless.

 

So I put on my 10th grade geometry hat and figured it out.  Here’s what I did. 

 

Goal:

 

Use simple geometry to determine how many Nordictrack revolutions equal one mile.

 

First, measure the radius (r) of the encased wheel (this is the distance from the center to the outer edge). For improved accuracy, I measured from the center to the middle of the axle that attaches to the foot platforms. On my machine, the radius was 10 inches.  But we really need the diameter, which is 2(r), or 20.

 

So, we have the first part of equation, diameter (d): 20 ”

 

In order to determine the distance that the wheel would travel if it rolled freely, I need to measure to know the circumference of the wheel. This is the total length as measured all the way around the wheel, like you would get if you wrapped a tape measure around it.

 

Here’s where the geometry comes into play: since I cannot wrap a tape measure around the wheel, I use this formula to calculate the circumference (C):

 

 C = d(PI)

 

PI is that weird number that you remember from school. I won’t even bother with any details; for this explanation we’ll just agree that it is an important number and we’ll say it is 3.14159265.

 

So, the equation starts to take specific form:

 

C = 20(3.14159265) or C = 62.831853″

 

Now that we have the C, we can calculate the miles per revolution. To do this, first convert C, which is in inches, to feet:

 

62.831853″ = 5.236′

 

Now we know that every time the wheel revolves one complete turn (a revolution), we theoretically have traveled 5.236 feet. How many equal a mile? One more calculation:

 

5280 feet / 5.236 feet = 1008.4 revolutions

 

So, to travel one mile on the Nordictrack you have to pedal 1008 (or so) revolutions.

 

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  • Becki

    wow. how ridiculous is it that Nordictrack couldn't just have a setting for mileage???? We have had our machine for about a year and I noticed the distance issue immediately. I asked my husband to look into it and he came back to me saying, ” I found only one site online where a bunch of people were calculating strides and it seems complicated – I can't really explain it to you, you should go and check it out.”

    While I have two SMALL children and work full time, I found this to be a great excuse to not focus on me and my working out!! All because of a reporting distance issue. Now, a year later, I am on a mission to put me first again and have worked out every day for 10 days so far.

    The distance was bugging me so I got online to see what I could find out. I didn't remember until I reached the end of all these posts, that I had my husband research this a year ago ( I had completely forgotten). I do believe this is the same site he had found last year and I find it incredulous that I did to and its still the only one addressing this issue!!!

    So thanks to all who have posted. I will be taking some notes tomorrow when I get back on the elliptical. Off the top of my head though, I think somewhere between the 586 and 1008 seem most likely for me! Thanks to all!

  • John Minnihan

    Thanks, Becki.

    I agree that the vendors should make this data available on their websites. But, as you can tell from this discussion, there isn't universal agreement on exactly what to measure or how.

    So for now, I'm happy to let this post act as the clearinghouse for this question.

  • Doug

    In each revolution, your foot travels the circumference of an ellipse with length of 51 inches and height of 22 inches. That comes to a “stride” of roughly 123 inches or 11 ft. That puts a mile at 480 revs. At my normal pace of 50 rpms, that would give a 9.6 minute mile or roughly 6 miles per hour. This agrees pretty well with reality. Using the 1008 rev per mile and my 50 rpm pace would make my average mile 20 minutes, which is walking pace and I know I'm going at a jog, not a walk. However, using the factory estimate of 300 revs per mile would make my 50 rpm pace a 6 minute mile and I know that's not the case. So for a rough measure, I'm using 500 revs as a mile.

  • John Minnihan

    Hey Doug,

    Great analysis. What's the source of the ellipse dimensions you used?

  • http://www.healthwellnesstips.net/ health_and_wellness_tips

    Oh!…that's great helpful, it's so right to me! Million thanks for the article,

  • It is all in the stride !!!!!

    Your calculations are correct for the wheel portion only. Let me explain why. The wheel will roll freely a distance of 65 inches. (one revolution) BUT, the way the pedals are positioned while your body spins the wheel one revolution is much less distance traveled by the actual human body. Let's say you step forward 6 inches on the elliptical. You have turned your wheel 1/4 turn to do that. The wheel will then rotate another .75 and when you take your next foot forward you finish the last .25 to be equal to 1 rotation of the wheel. The wheel moved 65 inches forward but you only moved 12 inches forward. So in actuality the human body has only moved 12 inches forward per 1 revolution. In theory if you were using the pedals to power the elliptical and flat surface and it would move forward 65 inches per 1 revolution but you have only pedaled a stride of 12 inches to do that. So to accurately calculate how far the human is going and not the machine it would be 12 inches per revolution. In order for the human to stride 63, 360 inches (1 mile) you would need to divide by 12, so in actuality you would need to do 5280 revolutions to actually have physically walked 1 mile. The machine will go 1 mile in 974 revolutions. The machine moves much farther along than the human physically does. Remember one revolution moves the machine 65 inches forward. One Revolution only is equivalent to 12 inches for the human. This is important if you want to accurately calculate miles for the person and not the machine. A more accurate formula would be 2 X your stride length X the number of rotations equals your distance traveled divided into 63,360. Using this formula, if I did a total of 2585 revolutions I actually will have walked just under 1/2 mile, but the machine would have traveled 2.65 miles. So if you want to actually walk 1 mile on an elliptical machine you must do 5280 revolutions. Because the stride on the elliptical is not as efficient as the wheel distance you have to spend more time on the machine to accomplish the distance. It took me 78 min to go 2585 revolutions, I used a high resistance to burn more calories (1500) but I only physically traveled just under 1/2 mile. If you are not going to use high resistance you will burn fewer calories. Don't let this frustrate anyone from trying to achieve a mile it just takes you longer on an elliptical than it would a treadmill for example.

  • John Minnihan

    Thanks, great comments.

    As I've maintained since writing the post (now more than 2 years ago… hey!), I'm comfortable with my analysis & conclusion. Since the mileage travelled on an elliptical will always be theoretical only, there's no strictly right or wrong answer, and there's certainly no agreement on what to measure (ie.. what is rotating?)

    I continue to be amused & slightly humbled that this post has emerged as the authoritative reference on this question. I say today, as always: use whatever measurement makes sense to you.

    Enjoy.

  • hackmart

    John, All,

    The reason that it is so hard to find a definitive answer to the “revolutions per mile” question concerning elliptical machines is because the answer is fairly complex. Most of the geometric calculations I've seen here on your blog are correct as far as they go but are a measure of “machine miles” rather than the actual equivalent miles a person with a normal stride would have run on level ground.

    Elliptical machines only approximate a runner's stride – which is why most stride length measurements come up with really large numbers of revolutions per mile (1000+). If you were to adopt a stride on level ground like that of an elliptical you'd be taking really small steps. Movement on an elliptical machine is more akin to running uphill but with the ability to raise or lower gravity – so you can be running up something steep, with short strides, but with low resistance (if you choose).

    A much better way to approximate your mileage, as has been suggested by others, is the”work equivalent” mile. The calculations involved in doing this are both laborious and will vary somewhat from person to person. This probably accounts for the difficulty in getting a straight answer from NordicTrack or other manufacturers concerning this issue. The upshot is that for most individuals on machines with a 20″ stride length (or average stride length if adjustable) the work equivalent revolutions per mile is between 700 and 800 revolutions.

    I made these measurements on a NordicTrack Audiostrider 990. My body mass is about 92kg (205lbs) and I am 6'3″ tall.

    I hope that this helps. This blog is one of the highest rated in a Google search (which is how I found it) so I hope that this helps other runners make sense out of the confusing data supplied by their elliptical machines.

  • Ryan L

    Hey guys (John) I agree with your calculations mathematically, but logically they make no sense based on my experience! I just got off my 800 and I ran 364 “Distance” in exactly 6 minutes, now I am not in the same shape I was in, in my highschool days but I could easily run a 6 minute mile in those times. I was moving at a good pace and there is no way I could have kept up that pace for another 644 “Distances” which would have been a total of an 18 minute mile! The 300 estimate sounds much more realistic,have you watch. My only thought is maybe you are only calculating the revolutions that are completed by one foot, rather than two, which would put you at 504, rather than 1008, which makes a heck of a lot more sense to me (and would explain my being out of shape!! haha) The main reason it's confusing for me is that the machine doesn't count revolutions, it just says “Distance” whatever that means! The questions is how many revolutions are in one “distance” is it 1 or 2???

    Make any sense to you?

  • David Nelson

    Hi John,

    I found the link to this conversation in January. It really is the only ongoing conversation. You can't get this stuff from Nordictrack. I tried and their 3rd party support people sent me a cycle conversion. They admitted they did not have anything for the elliptical after I called them on it.

    I recently got a 990 pro Audio Strider. Real nice system that gives a good workout. My search started because in the gym I use there is LifeFitness systems. Nice commercial item that measures in MPH and Miles (theoretical miles). They do meet at the 18inch stride setting so I thought it would be simple to find a way to figure this out. Key word “thought”.

    I started with the basic 1760 strides count and realized pretty soon that this could not be right. I liked your calculation method but it still did not work for me 100%.

    I had decided to just not worry about it and focus on effort and time. I guess us analytic types just can't.

    So, I have taken some less than 100% accurate measurements to back into the Rotations Per Mile (2X = Strides). I have worked my way up to 40 minutes of solid work on both systems. During a recent LifeFitness session the indication was 3.59 miles total or 5.385 MPH. As I vary the resistance the first mile is faster 5.825 MPH. During the first mile I counted rotations for 2 minutes. I got an RPM of 67.

    Basically what I calculated was 690 revolution = 1 mile. I used this to back into finding R and got 14.6 inches. Well the well is not that big. It's pretty much the same as the 990p system.

    This 690 RPM doesn't translate directly to the 990p. I hit this many revolutions in much less than 10-11 minutes and I know I am not moving that much faster.

    So then throw all that out. Differences in manufacturing styles kind of blow out comparing 2 systems. You can't count on the Pulse count on the systems either.

    What I can say for sure is on the gym system my current effort gives me about 3.6 miles on 40 minutes. On the 990p I get about 4500 strides. Both of these get me to the point of needing to wring my shirt out and I need to stop.

    If someone wants to get a pedometer (and I might) you need a good one. Consumer Reports likes the Omron Pocket Pedometer HJ-112 best. From reading about it you should get an accurate reading from walking as well as on the elliptical.

    In the end we might forget all of this and focus on the cardio aspects. Getting your heart rate to your target (220-age) for 15+ minutes. Of course you will need a good pulse monitor.

  • Nicole

    I own the audio strider as well, and was wondering how to figure out the measure of distance it was using. this was soooo helpful to me, and now i know that when i see 1,600 i know that it means i have gone over a mile! thank you so much for this!

  • John Minnihan

    Hey folks – thanks for the visits & recent comments.

    I get a chuckle out of the fact that this post seems to remain the authoritative discussion on this topic, well over two years since I wrote it.

  • RT

    Many of these calculations seem logical, but as some have mentioned, simply converting a machine rotation to a distance to derive a running (or biking) distance is very complex. Not only is it dependant on the machine, elliptical geometrics and incline, it also has to do with the resistance selected. Since this is almost negligible when running on a flat surface, the best way to approximate the distance is to take the amount of calories burned into account.

    I'm in the Navy and they require a bi-annual fitness test which, in part, relies on time to complete a 1.5-mile run. Not to long ago they have allowed the use of stationary bikes and elliptical machines to complete the cardio portion of the test. The caloric data from 12 minutes on the machine is plugged into a calculator with the model of machine used to give an equivalent 1.5-mile run time. This method supports the idea that the distance can best be determined from the amount of calories burned and how the machine calculates those calories.

    Anyone interested in downloading the “elliptical and bike calculator” can get it at http://www.npc.navy.mil/CommandSupport/Physical… (link is on the right side of the page.) You will notice that NordicTrack's AudioStrider is not on there, but if you use one of the models listed, you will see that it is fairly accurate.

  • John Minnihan

    Hey, thanks for the comments & the link to that calculator tool. That will be helpful to lots of folks.

    And you're right – this is a complex problem because there are simply too many variables over which we have no control. Declaring a constant, such as an 8-minute mile as used in the Navy model, allows us to normalize away these variables & plug assumptions into our model, which is the approach I took as well. (“determine the distance that the wheel would travel if it rolled freely”).

  • Renee

    Thank you so much for launching this discussion. I know you have to be continually amazed at its ongoing nature, but it's just evidence that we really want to know how far we've gone if we work up a dripping sweat on this piece of machinery. And the answer seems to be: Not nearly as far as we'd thought! Which is probably why Nordic Track avoided the whole question! : )

    I know there's no question I burn more calories and get my heart rate higher on the elliptical than I do by walking….I think I will just stick to measuring my walking miles and concentrate on the fact that when I use my elliptical, I am doing something good for my cardiovascular health.

  • Linda

    Thank you John Minnihan – really appreciate the information. :)

  • http://recumbentexercisebikesreviews.com/ Recumbent Exercise Bike Review

    Thank you for sharing your calculations. I really appreciate this article.

  • Jim in Alaska

    You rock! My GED educational dilemma was solved by your equation! My 12 year old son was rattling off the numbers as I was reading your above work!

    Thanks!
    Jim in Alaska

  • John Minnihan

    Glad to hear that. Thanks.

  • Melissa in Utah

    Thank you for the explanation and also the formula–I actually feel a little smarter for it! The million dollar question is: Why doesn't Nordic Track just put it in mi/ki in the first place?

  • Dcary01

    The theory is correct, the items used in the equation are wrong. Distance traveled is determined by your feet and the circumference of that motion rather than the tire.

    • http://freepository.com John Minnihan

      Thanks.

  • Tabathaforsyth

    also, on the odometer where it says a number x 100
    The number, say…10 is equal to one mile…. so if you did 15×100 it would be 1.5 miles…

  • Hulaookes

    I’m not refuting your theory due to it’s mathematical evidence, but it seems a bit off. I use two different ellipticals, and it takes me about 35 minutes to complete 2.2 miles on one of them, and if your theory is correct, it takes me about 20 mins just to finish >1 mile on the Nordictrack one. Therefore, my question is how fast does your RPM on the Nordictrack have to be in order for
    this to be true?