Join Date: Aug 2005
Location: Pittsburgh, PA
Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
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Originally Posted by LarDasse74
700c is hardly a 'metric' size, nor is 28" the imperial size - they are 'names' for the size... the metric size is 622mm.
Yes, it's a metric size. The original dimension referred to the outside
diameter of the rim and tire combination being (about) 700 mm. In fact there were three "700" sizes, 700A, 700B and 700C, using various tire widths and rim diameters but all being about 700 mm outside diameter.
The mish-mash of names and sizes was finally rationalized by the European Tire and Rim Technical Organization (ETRTO) which defined wheel sizes by the rim's bead seat diameter so a "700c" rim is defined as 622 mm and a "27"" rim is defined as 630 mm.
The outside diameter of a current 700c rim with a 23 mm tire is about 668 mm but when the size was first named, tires weren't that small. However, a 39mm tire on a 700c rim would be about 700 mm in outside diameter.
Last edited by HillRider; 08-24-08 at 10:34 AM.