Bicycle Mechanics - 50/34 Chainrings compatible with Campy crankset and Dura Ace cassette

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kokopelli99
02-02-12, 08:07 PM
I'm building a bike for the first time, a 9-speed road, utilizing used parts from another bike. I've got a Dura Ace cassette and a Campy crankset. I want to change the chainrings from 53/39 to 50/34. Does anybody know if there are any 50/34 chainring sets that would be compatible?

FastJake
02-02-12, 08:16 PM
You have the appropriate crankset right? The crankset with the 53/39 is almost certainly 130BCD, the smallest ring that will fit is a 38T.
Al1943
02-02-12, 08:18 PM
A campy crankset with 53/39 chainrings will have a 135 BCD (bolt circle diameter) and will not accept a 34 chainring. It would be cheaper to buy a 50/34 compact crankset with matching bottom bracket of a different brand. And this should be compatible with your D-A cassette. The shifters, if indexed must match the number of cogs and cog spacing of the cassette (9-speed Shimano).

HillRider
02-03-12, 08:57 AM
Al1943 is correct that a Campy 53/39 double crank will have a bolt circle of 135 mm (130 mm is Shimano and nearly everybody else) and the smallest chainring that will fit is 39T. You will need a 110 mm bcd crank (aka "Compact") to use the 34T chainring.