Originally Posted by
thirdin77
You might need a bigger chain if you plan to size the chain according to the big ring/big cog method which is mostly meant to give you a long enough chain if you somehow mistakenly shift into your big/big combination.
His current setup has a 53-tooth large chainring on the front and a 27-tooth in the rear. Switching to a 52/39/30 triple crank along with the same 27-tooth rear cassette shouldn't require an
increase in the length of the chain, assuming it was properly sized for the 53-27 combo. Not much difference between 53-27 and 52-27...