# other than chainring size, whats the diff between a double and compact?



## LOUISSSSS (Dec 14, 2009)

How do i "convert" a road bike with a double Shimano Ultegra crankset with 53/39t chainrings into 50/34t gearing?

Is changing the chainring sizes all i need to do?


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## fun2none (Mar 16, 2010)

You will need to buy a compact crankset as the chainring BCD (bolt center diameter) are not compatible. Standard cranks are 130mm vs 110mm BCD for compact.


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