So, thinking yet again about a drivetrain upgrade for my road bike. It's a c. 2006 stock Cannondale, originally second or third shelf from the bottom. The aluminum frame is actually a good one and suits me well. (I think it's essentially the same one that continues to get good reviews even now from the bike mags, in the "affordable race bike" sector, broadly speaking.) In any case I'm not prepared to shell out for a new bike. Have a few component improvements on there already, including bars, wheels, saddle (thanks, Finndog), and pedals. A set of SRAM Force calipers is on the UPS truck now to oust the squishy Cannondale-branded Tektros or whatever they are.
Anyway, the drivetrain is the confusing nut to crack because of all the pieces that have to play nice together, so I keep putting it off. Currently the bike has a triple crank, which I'm very anxious to replace with a double, for reasons of weight and (mostly) simplicity. (I virtually never use the granny, but every so often I end up dropping the chain onto it accidentally at a very inopportune moment, and it bugs me.) It's a nine-speed setup. So my question is: which parts can I re-use, and which parts must be replaced? Can I just through a new (to me) crankset on there? Do I need to look for an older version that was designed to work with a 9-speed chain (if such a thing is even still available)? Or does it just not matter with chainrings the way it does with rear cogs? What about the front shifter and front derailleur? Absent contrary info, I'm going to assume I can just make that work with two rings, same as I have done several times with MTB triples where the big ring has been replaced with a bash.
Note: I understand that wear on the chain may force me to replace that and possibly the cluster in turn, regardless of whatever else I do. Let's say, hypothetically, that I was interested in going to a 10- or 11-speed configuration. Is that even possible? The shifters would have to be replaced. I think that's the big price hurdle. What about the rear derailleur? It's a perfectly functional Ultegra unit that I don't have any particular wish to swap. Frame spacing? Is the distance between the dropouts the same for a 10-speed as for a 9-speed?
This is a question that must come up pretty often for you shop rats.