What is 700cc a measurement of in a wheel set?
I teach 5th grade math and we did an activity on the circumference of a circle using the front wheel off my Specialized Sectuer as a manipulative. We measured the circumferance of the tire on the wheel and it measured out to be approximately 84 inches which converts to approximately 213.5cm. So, what does the 700cc stand for?
Thanks, Bert |
THe wheel size is '700C' not cc... cc is a unit of volume: cubic centimeter. (edit 1) Hopefully you already know that, being a math teacher :D
700C today refers to a rim with a bead seat diameter (BSD) of 622mm. Many years ago there were 700A, 700B, 700C and 700D wheels. Each had a different size rim and tire set that resulted in a nominal diameter of 700mm. Modern 700C wheels are used with tires from 18mm (super narrow racing tires) to ~75mm wide (wide '29er' mtb tires which also use 700C rims) so there is great variation in the diameter. But the rim size remains the same. (edit 2) 700A, B, and D are obsolete. GT made a few hybrid/cruiser bikes a while back with 700D wheels, and if you have one of those today and the tires wear out you basically need to buy a new bike. Other wheel sizes that used a similar system are 650B (medium width tires used on old dirt path and 'camping bikes, I think, as well as many modern mtbs) and 650C (small racing wheels used for an aerodynamic advantage in time trials and triathlons) (edit 3) Read this: http://sheldonbrown.com/tire-sizing.html |
700 mm is the (approximate) outer diameter of the rim WITH a tire mounted. The "c" was an old designation for a tire/rim type. There WERE "700a", "700b", etc... but those are long gone.
(It's 700c, not 700cc) LarDasse beat me to it, and his explanation is much better. |
Think of tire "sizes" as labels. It's kind of like clothing sizes. The labeled size is kind of but not really the measured size. Andy.
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Originally Posted by teachme
(Post 14896184)
I teach 5th grade math and we did an activity on the circumference of a circle using the front wheel off my Specialized Sectuer as a manipulative. We measured the circumferance of the tire on the wheel and it measured out to be approximately 84 inches which converts to approximately 213.5cm. So, what does the 700cc stand for?
Thanks, Bert |
Originally Posted by LarDasse74
(Post 14896277)
700A, B, and D are obsolete.
Originally Posted by TampaRaleigh
(Post 14896278)
There WERE "700a", "700b", etc... but those are long gone.
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Originally Posted by Doohickie
(Post 14896363)
Divide 2135 by 700. What do you get? (It's off a bit, but it should be pi; 700 refers to the nominal tire diameter at the tread. Kind of. Tire sizes are very weird.)
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Originally Posted by Doohickie
(Post 14896363)
Divide 2135 by 700. What do you get? (It's off a bit, but it should be pi; 700 refers to the nominal tire diameter at the tread. Kind of. Tire sizes are very weird.)
|
Originally Posted by LarDasse74
(Post 14896277)
THe wheel size is '700C' not cc... cc is a unit of volume: cubic centimeter. (edit 1) Hopefully you already know that, being a math teacher :D
Originally Posted by LarDasse74
(Post 14896277)
700C today refers to a rim with a bead seat diameter (BSD) of 622mm. Many years ago there were 700A, 700B, 700C and 700D wheels. Each had a different size rim and tire set that resulted in a nominal diameter of 700mm. Modern 700C wheels are used with tires from 18mm (super narrow racing tires) to ~75mm wide (wide '29er' mtb tires which also use 700C rims) so there is great variation in the diameter. But the rim size remains the same.
(edit 2) 700A, B, and D are obsolete. GT made a few hybrid/cruiser bikes a while back with 700D wheels, and if you have one of those today and the tires wear out you basically need to buy a new bike. Other wheel sizes that used a similar system are 650B (medium width tires used on old dirt path and 'camping bikes, I think, as well as many modern mtbs) and 650C (small racing wheels used for an aerodynamic advantage in time trials and triathlons) (edit 3) Read this: http://sheldonbrown.com/tire-sizing.html |
Originally Posted by teachme
(Post 14896469)
I see... The 700 is just a label representing one unit of approx. pi. ??
700mm is the nominal diameter of the wheel with a medium width tire (~35 mm). |
Yeah, I didn't mean to typ cc, but was confused if the "c" meant centimeter. So the "c" is a label not a unit of measure? |
Originally Posted by LarDasse74
(Post 14896504)
Not sure what you mean.
700mm is the nominal diameter of the wheel with a medium width tire (~35 mm). |
Originally Posted by teachme
(Post 14896534)
Is that where the 700 comes from? The measure of diameter in millimeters?
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I might be wrong from a historical perspective, but I don't think the number 700 has any specific meaning today -700c just identifies a standard.
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Originally Posted by Andrew R Stewart
(Post 14896285)
Think of tire "sizes" as labels. It's kind of like clothing sizes. The labeled size is kind of but not really the measured size. Andy.
I have had 4 bikes with 26" inch rims that were all different diameters. Like to drive me shugbit |
Using bicycle tires to try to show how things are measured is kind of like wading into the deep end. There is a lot to bicycle tire sizing that is not really obvious.
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Originally Posted by Rootman
(Post 14896595)
Yes, millimeters, the C is just a designator of the rim width, as already pointed out there used to other widths named A, B, and D with A being narrowest and D the widest, C was the most commonly used so they just went with C's as the standard 700 mm rim, discontinuing the others for the most part. They are also called 29 inch rims : https://en.wikipedia.org/wiki/29er_%28bicycle%29
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cc is a measure of Volume not length. Cubic Centimeters.
[Don't they consider the metric system, subversive, in Texas?] The numbers that count are a agreement between Tire/tyre and Rim Manufacturers. They use a tire-bead seat diameter.. for 700C it's 622mm. so look at tire sidewalls 622-32 is size & width.. Metric . nearest fractional size 27 x 1.25" is (approximate), a 630-32.. not same.. The ETRO numbers are on the sidewall .. circumference changes with tire width. of course.. |
Originally Posted by Andrew R Stewart
(Post 14896285)
Think of tire "sizes" as labels. It's kind of like clothing sizes. The labeled size is kind of but not really the measured size. Andy.
This. If you want the "real" size, look for the ETRTO designation |
Originally Posted by teachme
(Post 14896469)
I see... The 700 is just a label representing one unit of approx. pi. ??
|
Originally Posted by jim hughes
(Post 14896607)
I might be wrong from a historical perspective, but I don't think the number 700 has any specific meaning today -700c just identifies a standard.
|
Originally Posted by teachme
(Post 14896469)
I see... The 700 is just a label representing one unit of approx. pi. ??
Originally Posted by wheelreason
(Post 14896911)
Step away from the students,....SECURITY!....I'm ordering a Mandarin Rosetta Stone immediately...
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Originally Posted by FastJake
(Post 14897070)
I'm still wondering what "one unit of (approximately) pi" is...
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Originally Posted by FastJake
(Post 14897070)
I'm still wondering what "one unit of (approximately) pi" is...
mmmmm, pi. |
Originally Posted by FastJake
(Post 14897070)
I'm still wondering what "one unit of (approximately) pi" is...
http://upload.wikimedia.org/wikipedi...rolled-720.gifhttp://bits.wikimedia.org/static-1.2...gnify-clip.png |
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