Bike sizes: metric vs. inches?

Why are road bikes in the US measured in centimeters and US mountain bikes measured in inches? I am sure the mountain bike was a US original, but why do we measure road bikes in centimeters?

If you look at the world at large, only two countries still use the archaic English system of measurement. The British, and the United States. Everyone else uses the metric system.

Cycling is still very largely a european sport, and as such, road bikes are measured in centimeters.

Even mountain bikes are starting to use metric measurements with regards to their frames. Bikes are now being marketed as small, medium, large, and so on. However, when you take a deeper look at the frame specs, you'll find nothing but metric measurements.

The same reason mountain bikes are in inches. Road bikes, until Trek and Cannondale came along, came from Europe. There were the English (Raleigh) and the Italian (Gios, Bianchi, Colnago). All made of chromoly steel, just like they should be.
As I'm sure there is some merit to the mountain bike measurement and road bike measurements and the areas of which they are from I think it comes from the type of riding on each of the bikes. generally on a road bike you will be spending much more time on the bike and increasing sizes 2cm at a time (most standard production) is a way to increase probable fit.

Also concerning product, the states try to run as low of inventory as possible thus running fewer sizes so they are able to standardize by using inches. It would be pretty confusing to walk into a bike shop and have a couple of road bikes sitting side by side and one is a 18" and the other is a 18-3/4".
metric measurements are more precise. and with a sport that is obsessed with perfection metric measurements is the only logical option.
as far as mnt. bikes, the fit has more room for error, making inches acceptable. or it could be a gimmick to appeal to the american masses.

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Kids Bike Schwinn Bike Cruiser Bike Road Bike Folding Bike Mountain Bike

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