# Old 27" road bike wheels vs 700c - question



## Rambo (May 23, 2010)

I have a 1970's road bike with 27" wheels.

Newer bikes have the 700c wheels.

I understand that 27" wheels are 630mm tall and 700c wheels are 622mm tall.

If in fact the newer 700c wheels are 8mm shorter than the old 27" wheels - My question is: If the 27" wheels are slightly taller, then WHY are 700c wheels often refered to as 29" wheels??


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## marcski (May 23, 2010)

Rambo said:


> I have a 1970's road bike with 27" wheels.
> 
> Newer bikes have the 700c wheels.
> 
> ...



I've never heard that reference.  29" wheels are a separate wheel size..for mtn bikes as opposed to the "standard" 26" mountain bike wheel.  There are lots of threads that deal with the pros/cons of 29" wheels vs. 26" wheels for mtn. bikes.


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## Rambo (May 24, 2010)

marcski said:


> I've never heard that reference.  29" wheels are a separate wheel size..for mtn bikes as opposed to the "standard" 26" mountain bike wheel.  There are lots of threads that deal with the pros/cons of 29" wheels vs. 26" wheels for mtn. bikes.



I was confused about wheel sizes. I found a chart which lists all the sizes and their perspective measurements.


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## dcarbs (May 24, 2010)

700C wheels are known as 29" wheels because with the thicker mountain bike tire the outside diameter of the tire is just below 29 inches.


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## Rambo (May 25, 2010)

dcarbs said:


> 700C wheels are known as 29" wheels because with the thicker mountain bike tire the outside diameter of the tire is just below 29 inches.



That seems clear up, the confusion I had. Thanks!


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