Compact Cranks and chain length
On my current bike, I've already perfected the chain length using the method Sheldon Brown recommends. This is on a 10 speed Ultegra double 53x39 setup, with a 12-25 cassette.
Now I just ordered an R700 compact crank (50x34), and a 12-27 cassette to help me ride up some serious mountains on an upcoming vacation.
So here's the question - I am going down 3 teeth in the front chainring, but adding two teeth to the largest rear cog, for a net difference of +1 tooth (I assume I'm correct on that part). Will I need to add a link to my chain to accomodate the new setup? I ordered a new Ultegra chain just in case, but I'm trying to plan the install in my head before the parts arrive.
Other than that I'm good on the install. Here's one weird thing though, the Ultegra chain that came on my bike actually has a SRAM style master link from the factory (LBS says it came that way, they didn't add it), which is nice. Hopefully the new chain I ordered will have one, making my standard to compact conversion an easy process whenever I'm lucky enough to leave the flatlands of Florida.
I debated on whether I needed to drop money on a new cassette to get the 27 cog, but figured it couldn't hurt me in the mountains, since it still has a low cog of 12 for those wicked descents.