project

[skianduniaddict]

im doin a school project for math how many wheel revolutions does it take to go a mile does cranks affect how bout wheel size?

[Smeltz]

You need to find the outside circumfrence of the tire, because that will differ depending on your tire.

An easy way to find the circumfrence is to measure the height of the tire (while the tire is on the wheel). then the Circumfrence= Height x 3.14.

Measure in feet and convert it to a decimal. (ex. 1 ft and 3 in = 1.25 ft)

Now there are 5280 feet in a mile. so divide 5280 by the circumfrence and that is the number of rotations it takes to go a mile.

Of coarse the answer will be different depending on the wheel and tire you measure.

Let us know the results!

[Smeltz]

Crank length wont effect this number, but it may effect how fast you can ride the mile!

[skianduniaddict]

i did it differnet ly but i have a 129 in math and have verified it with 3 differnt sources here r the results
36"-1760
29"-2190
26"-2444
24"-2640
20"-3300
16"-4061

[Mikefule]

Originally Posted by skianduniaddict

i did it differnet ly but i have a 129 in math and have verified it with 3 differnt sources here r the results
36"-1760
29"-2190
26"-2444
24"-2640
20"-3300
16"-4061

Without checking the rest, I can see that the first one is wrong.

You have used the diameter, not the circumference.

A mile is 1,760 yards.
A yard is 36 inches.

The circumference of a wheel is Pi x the diameter, or 2 x Pi x the radius.

So, a 36 inch uni does Pi yards per revolution.

Counting Pi as 3.142


1760/Pi = 560 revolutions to the mile

To find the circumference of a wheel, take the diameter (20, 24, 26 etc.) and multiply by 3.142.

Now you have a circumference in inches. What is a mile in inches?

Simply, it is 1760 (yards in a mile) x 36 (inches in a yard)

1760 x 36 = 63,360

That means there are 63,360 inches in a mile. That's why old inch/mile maps were in 1:63360 scale.

So, take 63360 inches (a mile) and divide by the circumference in inches.

Taking the Coker again:

36 inch diameter x 3.142 = 113.112 inches circumference.

63360 / 113.112 = 560.15

The accuracy of your answer will depend on how many decimal places you take for Pi. From memory, Pi = 3.1415926535 approx.

[Smeltz]

Mike is correct. Those numbers are off.

He is saying exactly what I said.

But I am still not sure that the actual outside diameter of a coker tire is truly 36 in. Can someone verify this?

[Mikefule]

The outside diameter of a Coker tyre at normal pressure with no load is as near as dammit 36 inches. An allowance could be made for deformation under load, but as a percentage, this would be minimal.

Let's not do the whole project. Leave some challenge for the student.

[Eddbmxdude]

At this rate we will have done his maths project for him!

I wish i knew about the forums while i was still at school!

Rock on!
Edd

[Jerrick]

There is a thread about this form terrybigwheel, everything is very well explained in there, I suggest checking it out =p

[Smeltz]

Originally Posted by Mikefule

The outside diameter of a Coker tyre at normal pressure with no load is as near as dammit 36 inches. An allowance could be made for deformation under load, but as a percentage, this would be minimal.

Let's not do the whole project. Leave some challenge for the student.

Thanks, for some reason it makes me fell better knowing that.

It could also depend on how you define a mile. If it is a pre-marked distance then you would have to ride your uni in a straight line, which may be easy for some people, but not me!

[skianduniaddict]

sorry i blew thAT AND I HADED IT IN SO ITS redo time

[fexnix]

I'm sorry i'm not contributing in any way but this would have been so much easier if you used metric :P

[Smeltz]

Considering the orginal question was 'how many rev's to go one MILE', I dont see how using the metric system would help.

[BornUgly]

Everything would be easier if we used metric.

[skianduniaddict]

i have them i did wheel 63360"/(diameter x 3.14)
36"-560
29"-695
26"-776
24"-840
20"-1008
18"-1121