Shimano has spread world wide , so chances are better when you need stuff that is what shops will carry.
Factories Buy cranks by the Millions, they install them as they get them.
So although it comes as a " 48/38/28 " you are free to try to fit a 24t instead of the 28, to get the 4t lower gear.
1/2 the t count of the Big Ring...
Cautionary Tale:
I have had a Self Extracting Square Taper Crank simply force the ring, out stripping the threads from the crank arm,
when I tried to Use It.
./.
Last edited by fietsbob; 09-23-16 at 11:45 AM.