Monday, January 02, 2012

How to Calculate Revolutions per Mile on an Elliptical Machine

My roommate has an NordicTrack elliptical machine.  I used it a few times last year and in counting the miles towards 2011 in 2011, I estimated that I ran about one mile for every 10 minutes on the machine*.  I'll likely use it again this year, but this time want to get a more accurate reading for my distances.  The machine has a reading for calories burned and revolutions turned, but not for distance.  No problem.  A little algebra helps figure it out.

The elliptical machine is connected to a wheel (that's what makes your steps go up and down), and like a bicycle, you can measure how far you've (Striden? Strode?  Ellipticalled?) by measuring the diameter of the wheel to get its circumference.  If you divide one mile by the circumference, you'll get the number of revolutions it takes to go one mile.  Quite simple, really!

Start my measuring the wheel's diameter.  That's the distance from the center to the edge, times two.  My wheel's diameter is 21 inches.  The circumference of a circle is the diameter times π ( 3.14159265..), so for my wheel, that is 66 inches.  There are 12 inches in a foot and 5280 feet in a mile.

So the equation looks like this:

5280/(21π/12) = 960 revolutions/mile

If you need a better explanation, I got this information from  Thanks, Lance Armstrong!

*I underestimated my distances using this method.  My final total last year is short as a result.  Oh, well.

1 comment:

mrsjanet said...

I also had problems figuring out the distance on the elliptical but now I can impress my husband thanks to your post!

What about treadmills? I'm assuming the treadmill tracks the distance base off the length of the belt. What if my stride is longer one day and shorter the next? I don't know if it'll help but I have this treadmill - livestrong 15.0t. I checked out their website but has nothing relating to this.