I recently had a Shimano R-600 compact crank (50/34) installed on my 2003 Fuji cross. This replaced the original Ritchey Cross crank that was a 48/38. The rest of the drive system is all Shimano 105 with a 12-26 9-speed cogset.
The shop did a good job setting things up and it is running smoother than before the change with one exception. When I'm on the big ring, shifts from a larger to smaller cog can take four to six revolutions of the crank. But, when it drops, it drops in quick and locks right in. Shifting from smaller to larger cogs goes quickly.
It does not have this same problem when I'm on the small ring.
I know how to adjust deraileurs if they are over or under-shifting, and setting the hi and lo stops. But I'm not quite sure what to do about this. I could probably bring it back to the shop but that would likely mean leaving it for a day or two for what is probably a three minute tweak.
In case it makes a difference, the cogset is original to the bike and probably has about 4000 miles on it. I replaced the chain about 2000 miles ago. I am getting a new rear wheel a the end of the week, and that will have a new cogset and new chain installed along with it.
Thanks in advance for any suggestions.