General Cycling Discussion - tire size question

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sathor
07-20-11, 12:56 PM
I am confused after reading some things on Sheldon's website, in that I saw it reffering to 700c wheels being 29's, but being smaller than 27's, so does that make the following true?

26<29<27 because that sees odd to me, but it seems to be backed up in a few places.


RaleighSport
07-20-11, 01:55 PM
You are correct, and here's a thread with some info http://www.bikeforums.net/showthread.php/615810-27-quot-wheel-gt-29-quot

Retro Grouch
07-20-11, 02:04 PM
If you're trying to make sense about bicycle tire sizes, think again because it's not going to happen. The 26/27/29 size thing is actually one of the easier bicycle tire size things to explain.

Think of the tire section as being roughly circular (including the section that's contained within the rim). So a wider tire is also going to extend taller in the dimension away from the rim. A 700c rim with a narrow road race tire is going to have a smaller diameter than a 27" rim and (medium width) tire. If you put a big, fat mountain bike tire on a 700c rim, it'll stick up farther and it's diameter will actually exceed the 27" tire and rim.


Kayce
07-20-11, 02:14 PM
The inner area of the rim where the tire sits on a 700 wheel has a smaller circumference than a 27 wheel. A 700 rim is the same circumference as a 29er rim. The 29 comes from the approxomite circumference of the fully inflated mtb tire on the rim.