bear with me, 'cause i'm a newbie here & newbie to dealing with these sort of mechanics (not a newbie to mechanics or bikes in general)....I just got a solid, but well-dated (technologically) Cannondale road bike for my wife. It still has the original 105 componentry, 6-speed rear, downtube shifters, and double front biospace chainrings. I'd like to add a triple chainring in the front & if it's at all possible, I'd be interested in looking at upgrading to at least a 7-speed rear (for the purpose of being able to add integrated brake/shifter controls). My question is what information do I need to get from the bike & what do I need to research to be able to answer. In truth, I don't even know the model #, but I guess I'll start with a serial number. I'm hoping I can find inexpensive cast-offs that can be used as pretty decent upgrades for her bike 'til she's ready for something more modern. Thanks in advance.