700c x 28c = 29?

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700c x 28c = 29?
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flag dmtx
Posted: Feb 10, 2012 at 14:40 Quote
I need to replace my wife's wheelset that has 700cx28c spec. I'm trying to shop around but not really sure what to get. Her bike is a hybrid bike (Rocky Mountain RC50) and has disk brakes. Is this wheelset the same spec as the 29er wheelset?

I'm not familiar with this and your help is much appreciated. Thanks!
flag typecaRl
Posted: Feb 10, 2012 at 15:21 Quote
700c relates to the diameter of the wheel. I believe it relates to 700mm which is 27 and a half / 28 inches its like the European standard because there used to be loads of weird sizes so they made it easier by just calling it 700c 28 relates to the width of the tyre. Again I believe 28mm
flag bernbikeshop
Posted: Feb 10, 2012 at 16:08 Quote
yes hybrides 700c wheel have the same diameter as 29er. 622 is the number you need for tire to fit
road bike are 622x23c, hybride are 622x28c-38c maybe even bigger and 29er are 622x47c and +
flag road-psyclist
Posted: Feb 10, 2012 at 16:13 Quote
700c is the wheel size, like 26" is 26 inch and 29" is 29 inch.

28c is width of the tyre in millimetres.

You'll need 700x28c or less (25c or 23c) as 30c or above may be too big for the clearance on your wifes bike.

Hope this helps...
flag bernbikeshop
Posted: Feb 10, 2012 at 17:16 Quote
kinetic-uk wrote:
700c is the wheel size, like 26" is 26 inch and 29" is 29 inch.

28c is width of the tyre in millimetres.

You'll need 700x28c or less (25c or 23c) as 30c or above may be too big for the clearance on your wifes bike.

Hope this helps...

I think he is shopping for wheels, not tires
flag hampsteadbandit
Posted: Feb 11, 2012 at 13:35 Quote
what you need to know is the rim diameter (ISO 622 for 700c)

a bike is considered a "29'er" when the tire size is 2" or above

when you mount a 2" tire to a 700c rim you get a measurement of 29" from the top of the tire to the bottom of the tire, measured across the wheel surface

anything smaller than 2" tire will not give a 29" measurement and is considered a cyclocross tire (i.e. 35C) by the 29'er community

to answer your question, all 700c road, 700c hybrid and 700c (29'er) mountain bikes use the same 622 measurement rim, what matters is the width of the rim (this determines the safe usable width of the tire) and the amount of tire clearance in your frame / fork as this would stop you using bigger volume tires than your frame / fork have been designed around

on my Specialized Crosstrail I have 700c Mavic A319 rims running skinny Specialized road racing tires (700c x 23c) but can run up to 45c on those rims, and probably have enough clearance to mount a Specialized Ground Control 2.1" 29er tire if I wanted to!

on many of the road bikes we see in our workshop, you cannot even move from 23C, to 25C or 28C because there is not enough clearance in the rear frame stays
flag deeeight
O+
Posted: Feb 12, 2012 at 13:43 Quote
typecaRl wrote:
700c relates to the diameter of the wheel. I believe it relates to 700mm which is 27 and a half / 28 inches its like the European standard because there used to be loads of weird sizes so they made it easier by just calling it 700c 28 relates to the width of the tyre. Again I believe 28mm

700C is an industry wheel code. The number has nothing to do with actual millimeters though. 29ers use the 700C wheel size as do MOST (but not all) road bikes, touring bikes, hybrids, and TT bikes. The code refers to the ISO bead seat diameter of the tire/rim combination, in this case its 622mm. Traditional 27" x something tires and wheels are 630mm ISO. The usual reason for confusion/overlap is that most innertubes made for 27" are often labeled on the box as 700C also.

Other sizes possibly to be encountered include the 27" size, 650A, 650B, 650C, 700D (rarely but a few are out there), 650B and 700D are so close in bead seat diameters (584 to 587, only a 3mm difference) that most 650B tires can be fitted to 700D wheels.

As already explained, the 29er part of a tire size relates to the mounted and inflated diameter being 29" (or more). Some 29er labeled tires don't actually reach 29" diameter though, and some 700C labeled tires do pass a 29" diameter. It largely depends on the actual tire casing and manufacturer (and how they measured the tire, by tread width or casing width). Bontrager XR 29 x 1.8 tires for example are only about 28.4" actual diameter, but Kenda Karma 29 x 1.9 are about 28.95" actual diameter. The difference lies in the fact the Kenda the width is the casing of the tire and with the Bontrager its the tread (the casing width is only 1.6"). The wider a casing gets, the taller it gets also.

http://sheldonbrown.com/rim-sizing.html
flag dmtx
Posted: Feb 13, 2012 at 11:52 Quote
Thanks guys! I got more info now to shop for a new wheelset. Much appreciated!
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