The front stays the same at 52/36. The smaller on the rear also stays the same. I was just worrying if the change from 28 to 25 on the rear larger cog will make too much of a difference to make the chain slack.
The chain is not new/old (well, it's KMC X11 SL, with about 8000 clicks on it, so I believe it still has life in it). It's well kept though.