You might want to measure the chainline so that you can calculate what happens when you use a different length spindle. Also if you care about symmetry, you should measure the distance from the center of the frame to the outside surfaces of each arm. So you will know what happens when you change to an asymmetric Shimano spindle.
Edit- I looked in their website but they don't show the inner chainring. Is it using a standard 8 or 10mm bolt hole in a flat chainring with 12mm diameter bolt head? If so, then you might be able to use cheap $10 74mm bcd chainrings in various teeth numbers, assuming that your current inner chainring has a much bigger bcd. But if it uses some special bolt hole size or flange shape, then a standard 74mm bcd chainring might not be compatible
Last edited by tomtomtom123; 12-05-19 at 09:27 PM.