how do I convert revolutions to miles?

Hi can anyone help me with this. I bought a elliptical and the distance is in revolutions. I need to know how many revolutions equal a mile. I was told it was 300-350 revolutions to a mile. Is this correct?

[Robert Fogt]

It probably differs between manufacturers, and you'd have to contact them for that information.

1 mile = 5280 feet

If 1 revolution was 2 steps (ie right foot then left foot) and your step is 2 foot long, then:

5280 feet / 2 feet = 2640 steps / 2 = 1320 revolutions

If you can measure how long each stride is, and determine for sure how many steps/strides in each revolution, then you could calculate fairly accurately.

That wouldnt work for exercise bikes, just elliptical machines.

Thanks for the help so you think 1 mile is 1320 revolutions? Wow that is different from what Welso said they claimed 300-350 revolutions = 1 mile. Here is more info I have a Weslo Momentum 620 the stride is '13 and when I use it once I go round once right and left foot the revolution changes to 1.

Originally Posted by Robert Fogt

It probably differs between manufacturers, and you'd have to contact them for that information.

1 mile = 5280 feet

If 1 revolution was 2 steps (ie right foot then left foot) and your step is 2 foot long, then:

5280 feet / 2 feet = 2640 steps / 2 = 1320 revolutions

If you can measure how long each stride is, and determine for sure how many steps/strides in each revolution, then you could calculate fairly accurately.

That wouldnt work for exercise bikes, just elliptical machines.

[JohnS]

Lym,

You have to analyze the horizontal motion of the pedal. In one revolution, it returns to where it was (it corresponds to a left stride and a right stride). Your machine's stride is specified as 13" but you could measure it. Place a newspaper under machine (to mark on) rotate wheel slowly, and place a mark on paper vertically below the forward and rearward points of travel ot the toe tip (or any feature of the pedal) and measure the stride.

A mile is 5280 feet or 63360 inches. There are 2 strides in a revolution, so divide 31680 inches by the stride 13 inch/stride. I think your machine is 2437 rev per mile. Other machines have longer strides, 18" which would be 1760 rev per mile.

In normal walking, most people have a stride (one sided) of 30" or a pace (left and right) of 60". I'm tall, have a natural stride of 36" so any of these machines would force me to take "baby steps."

The difference between this figure and the 300 rev/mile claim may be exertion. The elliptical may require you to overcome resistance over more of the range of motion or overcome greater resistance than normal walking would require. If they have data to back it up, this "work equivalence" point of view would also have merit. We have directly related the horizontal movement to walking distance, but ignored effort.

Now I am really confused. Seems like the number keeps going up.

Originally Posted by JohnS

Lym,

You have to analyze the horizontal motion of the pedal. In one revolution, it returns to where it was (it corresponds to a left stride and a right stride). Your machine's stride is specified as 13" but you could measure it. Place a newspaper under machine (to mark on) rotate wheel slowly, and place a mark on paper vertically below the forward and rearward points of travel ot the toe tip (or any feature of the pedal) and measure the stride.

A mile is 5280 feet or 63360 inches. There are 2 strides in a revolution, so divide 31680 inches by the stride 13 inch/stride. I think your machine is 2437 rev per mile. Other machines have longer strides, 18" which would be 1760 rev per mile.

In normal walking, most people have a stride (one sided) of 30" or a pace (left and right) of 60". I'm tall, have a natural stride of 36" so any of these machines would force me to take "baby steps."

The difference between this figure and the 300 rev/mile claim may be exertion. The elliptical may require you to overcome resistance over more of the range of motion or overcome greater resistance than normal walking would require. If they have data to back it up, this "work equivalence" point of view would also have merit. We have directly related the horizontal movement to walking distance, but ignored effort.

[Robert Fogt]

I would go by what the manufacture claims.

But if I had to figure it out:

5280 feet / 12 = 63360 inches
63360 inches / (13 inches * 2) = 2436.92 revolutions

13 inches * 2 = 26 inches * 300 revolutions = 7800 inches = 650 feet = 0.12 miles

But 13 inches seems like a very very short stride, like baby steps. That probably is a typo.

[Robert Fogt]

Wow I type too slow.

[JohnS]

Great minds think alike.

The 13" claim troubled me, so I looked at several machines. 13", 15", and 18" all seem common. It is limited by the diameter of the wheel (at the point the linkage is attached). The pictures would appear to bear out the claim (as well as I can judge. All are basically four-bar linkages which convert rotary and reciprocating motion.

For me, they are baby steps and I'm sticking to my NordicTrack cross country sky machine.

Originally Posted by robert fogt

it probably differs between manufacturers, and you'd have to contact them for that information.

1 mile = 5280 feet

if 1 revolution was 2 steps (ie right foot then left foot) and your step is 2 foot long, then:

5280 feet / 2 feet = 2640 steps / 2 = 1320 revolutions

if you can measure how long each stride is, and determine for sure how many steps/strides in each revolution, then you could calculate fairly accurately.

That wouldnt work for exercise bikes, just elliptical machines.

very nice.. My problem only is the linear vel. Because the given on the problem are in revolution/ sec. How can i convert this revolution/sec to miles/sec??

Well, quite honestly there is not a direct conversion from revolutions to miles. And that's why most manufacturers give you distance in revolutions instead of distance in miles. It really depends on whether you want "actual" miles or "work equivalent" miles.

Most manufacturers will give you the stride length in the owner's manual. For example, the stride length on my elliptical is 18". And, 2 strides is equal to one revolution. If you don't have the owner's manual you can simply take a tape measure and determine how far one side of the elliptical travels from its furthest point of forward motion to its furthest point of rearward motion. Mulitply that by 2 and you have the total distance travelled for one revolution. This is the "actual" distance travelled.

The reason that most manufacturers give you revolutions is that the distance the wheel travels through one revolution is typically further than the stride distance. For example, if the wheel on your elliptical has a 20" diameter (typical for many Nordic Trac ellipticals), the wheel travels the circumference of the wheel through one revolution or approximately 62.83 inches (5.236 feet).

Circumference = 20" (pi) or 20" (3.14159) = 62.83 inches (divide by 12 inches/foot and you get 5.236 feet)

Realize that through the entire range of motion of the wheel on an elliptical part of the motion translates to up and down motion and not forward motion. However, you still have to expend energy in the form of work to move the wheel through that entire range of motion. So, you've actually done more work in one revolution than just the actual distance travelled by your stride length.

Using the example of my own elliptical, while the "actual" distance travelled for one revolution is 36 inches or 3 feet, you have in fact done work equivalent to travelling 5.236 feet by moving the wheel through one revolution (that's why I refered to it as "work equivalent" miles). Since there are 5280 feet in one mile, I would have to do 1760 revolutions to travel the actual distance of one mile. However, you do the equivalent work of walking one mile in 1008 revolutions (1008 revolutions x 5.236 feet/revolution = 5278 feet). Hope this isn't too confusing.

So, while converting revolutions to miles is not like comparing apples to oranges, it is akin to comparing MacIntosh apples to Red Delicious apples.

BTW, I can tell you from experience that I expend more energy putting 2.5 "work equivalent" miles on my elliptical than I do walking 2.5 actual miles through my very hilly neighborhood.

Hope this helps.