Just got my road bike back from the bike shop the other day.  I wore through my second drive train.  The bike is 11 years old now, and has a 9-speed cassette, and the new ones are all 10-speed.  To make a long story short, it seems that the chainrings for my old Shimano 105 triple crank set are no longer being made.  At the shop’s recommendation, I ended up switching to a compact double crank set.  The front derailleur and cassette also needed to be swapped out; I was able to keep my existing front shifter.

For those not familiar with compact crank sets, compared to a triple, they typically use a 50-tooth large chainring and a 34-tooth small chainring, and the cassette has a slightly wider range of gears, at the expense of slightly larger jumps between gears.  Compared to a triple, the small chainring splits the difference between the middle ring and the “granny” ring, and the largest cog on the cassette has a few more teeth.  You lose the very lowest and very highest couple of gears, but in theory, the setup is lighter, the chain lines are better and the drive train is less “finicky”.

I took my first ride with the compact this morning.  My biggest complaint with the triple was that the chain would rub the front derailleur cage in a lot of gear combinations, making them unusable.  The shifters have some extra index positions to allow for limited “trimming” of the derailleur, but with 3 rings, there wasn’t a whole lot of tolerance to work with.  With the compact, I found that I still need to trim the front derailleur, but with only 2 rings, I’m able to trim it more effectively and predictably.  Sometimes I wonder if I’d be better off with a friction shifter.  It might be old-school, but it would allow infinite fine-tuning of the front derailleur to match the position of the chain.

Anyhow, the jury is still out on the compact double, but it seems like it’ll be an improvement.  I’m still getting used to it, so stay tuned for further reports.