Gear Ratios

Audrey, is an older bike, a classic, but an older bike.  She has downtube shifters controlling a 12 speed transmission.  The gearing of the bike was set-up prior to cadence became the holy grail of cycling.  So I knew I was pushing some big gears, but not how big.  When I competed at the Boulevard road race I was a little jealous of everyone spinning up the hills and when I mentioned it to Chuck he told me, once again, that he could give me some more low end.  But for some reason I am resisting.

Now I have actually counted the teeth on my gears and I am running a 52 / 42 up front and a 13-21 in the back.  What does that mean?  I don't know, but I hope I am not destroying my knees.