Originally Posted by
Marcus_Ti
To get a 30T, you need a non Hollowtech crankset.....
Some older Hollowtech II cranks support 30T and even smaller chainrings. 105 FC-5703 cranks have 130/74 bolt circles and the inner bolt circle allows down to a 24T chainring. Tiagra FC-4700 and Ultegra FC-6703 cranks have no inner bolt circle but the middle chainring has a auxiliary 92 mm bolt circle and takes a 30T chainring.