Which Components to Upgrade

[OakLeaf]

And a question about rear derailleurs: How do I interpret the Maximum Chainring Difference and Total Tooth Capacity to know whether I need a short-cage or long-cage to pair with my 48/34 compact up front? Can someone explain what this means and how it should be taken into account?

Someone correct me if I'm wrong, but I'm pretty sure this is it: Maximum chainring difference is the difference in number of teeth between your largest and smallest chainrings. With a 48/34 it would be 14, so as long as the derailleur will accommodate 14 or more, you're good. Total capacity is your chainring difference plus your cassette difference - with a 48/34 and a 12-27 it would be 14 + 15 = 29, which is the maximum for a short cage Ultegra RD.