Originally Posted by
spdntrxi
50/34 and 52/36 are usuallly 110bcd while 53/39 is 130bcd... atleast on the brands I am familiar with so you cannot mix the rings and arms obviously.
Is this for 5 arm or 4 arm cranksets? I haven't made the jump to 4 arm yet, so for 5 arm cranksets,
You may also be able to do 52/34, by simply replacing one ring on either the 52/36 or 50/34. It may or may not affect your shifting performance, or a possibility of chain suck.
With the 110bcd cranks, you can also replace both rings to go between "compact" and "mid".
You may or may not be able to find 53/39 rings for your 110 bcd cranks.
Are 4 arm cranksets coming in different BCD diameters, or are they all the same? That might mean just sourcing new rings of the desired size.