Shifting problems can sometimes be difficult to diagnose.
This video will address some common sources of poor rear derailleur performance and how to fix them.
Calvin Jones here, Park Tool Company.
The most common fixes for shifting problems are the basics:
properly setting the limit screws,
and adjusting the index setting.
For a walkthrough of these procedures, watch this video.
However if you've already checked these settings and things still don't seem quite right,
here are some other issues to look out for.
The cable system is the housing and the inner cable together.
Dirt and grit can work their way inside.
This creates friction along the system, which will slow the shifting both directions.
On most bikes you can get a closer look at the cable by putting the bike in the lowest gear.
then without pedaling, shift the derailleur to slacken the cable.
Remove the housing from the stops.
Feel the cable and feel how the housing slides.
You can also wipe the cable and throw on some lube.
Put the housing back and see if it helps.
But if the bike has full housing without stops, that doesn't work.
You will need to loosen the pinch bolt to get a feel for how the cable is operating.
If it feels gummy, install new cable and housing.
Also inspect outside of the housing, especially at the ends.
Damage anywhere along the system isn't helping our shifting.
Replacement of the housing and the cable is the best option.
The rear derailleur is attached to the frame with a hanger.
This piece can get bent from crashing and bashing.
The pulleys are not going to align with the sprockets if the hanger is bent.
Check and repair it with a hanger alignment tool like the DAG-2.2.
Watch this separate video to walk through the whole derailleur hanger alignment process.
As bike components get replaced, there can be incompatibility issues.
This bike was in a crash and the rear shifter was smashed.
It's a ten speed, so we installed a 10 speed shifter, so all should be fine.
And testing it out, we get the smaller gears no problem.
But moving to the larger cogs, the chain is now striking the inward cog and making a racket.
Can't we just use the barrel adjuster to index this gear so it is quiet?
Yes, it worked on these gears, but now going back...
...the racket seems to have moved out here.
Turns out the issue is not indexing settings at all.
This aftermarket MicroShift shifter was not designed to work with a SRAM rear derailleur.
Another incompatibility issue could be having the wrong type of chain.
Chains vary not only in width for 9, 10, 11 and 12 speed, there are differences in side plate shapes.
The solution here, other than trial and error, is to stick within your brand and drivetrain model.
Chains take a lot of abuse, and they don't last forever.
The internal parts of the chain, the rollers and rivets, begin to wear down and give the illusion of stretching.
This wear can cause the chain to mesh poorly with the cogs and chainrings,
causing poor shifting and premature cog wear.
Inspect your chain to see if it falls within the limits of tolerable wear.
See this other video for a guide on checking for chain wear.
Check also for adequate lubrication.
A dry chain will feel sluggish when shifting and will make excessive noise when pedaling.
This chain looks dry and feels dry.
There is no lube that comes off when touched.
Add a drop of lube to every rivet, and then wipe off the excess.
All derailleurs wear out at some point.
Check this by pulling laterally on the lower cage.
Compare this movement with a new derailleur.
Sloppy pivots and parallelograms will produce inconsistent shifting,
and the only solution is a new derailleur.
That's it for advanced rear derailleur troubleshooting.
If you're still having shifting problems,
you can find more potential causes in our troubleshooting text article at parktool.com -
or bring your bike to an experienced mechanic.
Finally, be sure to check out the Park Tool guide to derailleurs
for an overview of all of our derailleur and shifting content.
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