you also need to take into account the wheel diameter...below see email I rec'd from Nordic track...for my machine(not the ex below mine is 851.6)
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): 20h
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.
Herefs 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 wonft even bother with any details; for this explanation wefll just agree that it is an important number and wefll 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.