"1954 mm 76.9 inches 700 C, 28 x 1 5/8, 29 inch
(28 x 1 1/2 F.13 Canada) 622 mm Most newer adult bikes for road use use this size,
including most road bikes and hybrids"
Quote from Sheldon (
http://www.sheldonbrown.com/rim-sizing.html)
"29 inch wheels / ISO 622
Main article: 29"er
“29-inch wheels”, which also conform to the popular 700C (622 mm diameter clincher wheel standard) are becoming more popular for not only cyclocross bikes but also cross-country mountain bikes for larger riders. Their rim diameter of 622 mm (~24.5 inch) is identical to most road, hybrid and touring bicycle wheels but are typically reinforced for greater durability in off-road riding. The average 29-inch mountain bike tire has an outside diameter of about 28.5" (724 mm). There are advantages and disadvantages associated with this change discussed in detail in the main article.
700C Road bicycle wheels / ISO 622
Touring, race, and cyclo-cross bicycles may have vastly different design goals for their wheels. The lightest possible weight and optimum aerodynamic performance are beneficial for road bicycles, while for cyclo-cross strength gains importance, and for touring bicycles strength becomes even more important. However this diameter of rim, identical in diameter to the "29er" rim, is by far the most common on these styles of bicycles. It rolls more easily than smaller diameter tires. Road wheels may be designed for tubular or clincher tires, commonly referred to as "700C" tires."
Wikipedia quote (
http://en.wikipedia.org/wiki/Bicycle_wh ... 2F_ISO_622) Note with the Wiki quote the same ISO number.
I agree it is very similar in size but when setting up a cycle computer you need to use the figures either on the tyre or in the instructions for it to be accurate.
And if you have been on ebay you will have seen this
http://cgi.ebay.co.uk/RARE-FIXIE-RACER- ... 2a08f29bb0 Made for 27" wheels.
They never were that accurate but each to their own I suppose.