Getting back to the original poster's problem:
Originally Posted by
MikeRides
I've got 900 miles on the bike, I usually stay in the 5th cog in the back and middle ring in front on most rides, but down shift on hills. Recently I've noticed when shifting from 4th to 5th that the chain has a hard time grasping the cog. I've never deep cleaned the bike before, and assume the stone dust trails I ride are gunking up my drive train causing this issue.
The chain isn't loose by any means or has any indication of wear but I've noticed if I drop the middle ring to the lower ring and shift the rear into the 5th cog i don't have a problem shifting so its definitely the 2 x 5 combo. The mechanic recommended using a can of White Lightning degreaser to clean up the derailleur and cogs, re-lube the chain, and see if that corrects the issue. If it doesn't I'll be taking the bike to him to look at.
As other posts above have said, it's likely just a derailleur adjustment. You should learn how to do it, so you can make minor adjustments as needed in just a few minutes.
See the section titled
Checking the Rear Indexing Adjustment on this
Park Tool Rear Derailleur page.
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My drivetrain cleaning methods.
I
never spray degreaser on the bike. I don't want it getting into the freehub or the bearings.
Wipe all the dirt off the chain and derailleurs. I dampen the rag or paper towel with rubbing alcohol. Scrape off any crud on the two pulleys.
Wipe off the chainrings. For the rear cogs, a folded paper towel with rubbing alcohol worked down into the gaps between cogs.
Relube the chain, and wipe off completely. The lube needs to be inside the chain. (I used to take off the chain with it's quick link, soak in mineral spirits, rinse and dry, then relube. It didn't seem to be any better than just wiping and relubing.)
Lube the pivot points on the derailleurs.
Once a year or so, remove the two pulleys, disassemble them, clean and regrease. Replace if the bushings are very worn.