How to Adjust a Rear Derailleur – Limit Screws & Indexing
Why Bicycles Stack Exchange recommends it
Bicycles Stack Exchange answerers link it when someone has skipping, slow or inaccessible rear gears and needs a visual walk-through of limit, indexing and B-screw adjustment.
Recommended by 9 people across 16 different months, 2011 to 2024.
What it is
A 16-minute Park Tool tutorial showing how to fix rear shifting problems by setting the H and L limit screws, the indexing (barrel adjuster) and the B-screw. A Park Tool mechanic demonstrates each step on a bike in a repair stand, with chapter markers for each adjustment.
What people said
Recommends ow3n · 2011-12 · Bicycles Stack Exchange · on “While pedaling standing up, bike crank gives in as if shifting, what is causing this?”
I would have started by noting which gear (front or rear) is slipping and adjusting the tension on the corresponding shifter/derailleur to bring it closer to correct adjustment. A rule of thumb is, make the adjustment and if it gets worse then you are going the wrong way :-) If the shop changed your chain did they also change the cassette (rear gears). The chain and gears usually wear together and cause the slipping problem so it is a good idea to change them both at the same time. UPDATE (2018) I've referred to these Park Tool videos many times to understand and adjust my drivetrain. Park Tool Guide to Derailleurs & Shifting: Introduction [LINK] (2:35) How to Adjust a Rear Derailleur – Limi
Recommends Argenti Apparatus · 2017-08 · Bicycles Stack Exchange · on “How do I mount rear derailleur on frame without separate hook part?”
Some Tourney derailleurs have a sort of extension ('hook' as you call it) that your new Acera derailleur does not. That is fine. The Acera derailleur simply bolts to the derailleur hanger on the frame (the piece if metal pointing downward in your first picture) Your new Acera derailleur has what is known as a 'B pivot' which I believe the Tourney derailleur lacks. The B pivot is located where the derailleur bolts to the frame. The entire derailleur rotates around the B pivot, the B pivot spring tries to rotate the derailleur anti-clockwise underneath the cassette. (There is also a 'A pivot', around which the jockey wheel cage . rotates.) The blue painted screw you mention is the 'B screw', w
Recommends Argenti Apparatus · 2017-12 · Bicycles Stack Exchange · on “Rear gears not shifting between 6 and 7”
Most probably the cable is too loose so that the derailleur is resting against the high (outer) limit when in the highest (smallest sprocket) gear, and there is slack that the shifter needs to take up before moving the derailleur to the next sprocket. Shift the derailleur to the smallest sprocket and make sure the shifter is on the highest gear setting, turn the barrel adjusters in to their slackest setting, undo the cable pinch bolt and pull the cable with a pair of pliers to take out slack and do up the pinch bolt again. If you have trouble getting slack out of the cable, a trick is to change gear to the second smallest sprocket, then without pedaling click the shifter back to the highest
Recommends Argenti Apparatus · 2017-12 · Bicycles Stack Exchange · on “Issue with the gears?”
I can infer that a new bike with 6 speeds in the rear is an inexpensive one. It's likely it was not set up correctly when it was assembled. The rear derailleur probably just needs properly adjusting. I'd recommend taking your bike to a local bike store and have their repair shop adjust the gears - it's a short procedure and will not be expensive. You should also ask them to have a look over the bike to check for other assembly or adjustment problems. If the gears were not set up correctly then something else may be wrong, which may cause a safety issue. If you want to tackle it yourself, rear derailleur adjustment can look daunting, but there are several good videos available with procedures
Recommends Argenti Apparatus · 2018-04 · Bicycles Stack Exchange · on “Chain not sliding into casette perfectly”
By definition, if the chain is not running on all cassette sprockets properly, the indexing and/or limits are not properly adjusted. Low limit setting being off would be my guess. Run through the full indexing adjustment procedure. Park Tool Company has the best instruction video [this video] . You can check the derailleur hanger by lifting up the rear wheel and looking down a line from the derailleur cage to the chainrings. The cage should look parallel to the rings.
Recommends Argenti Apparatus · 2018-09 · Bicycles Stack Exchange · on “What does this barrel adjuster do on the rear derailleur (SRAM Apex 1)?”
It lengthens or shortens the housing length to adjust the lateral position of the derailleur cage. It's used to adjust derailleur 'indexing' so that the chain sits properly on the cassette sprockets. Mountain bike shifter units have barrel adjusters, road bikes use this one as well as having frame mounted or 'in-line' adjusters some where on the housing run. This video from park Tool Company has a good visualization of how it works:
Recommends Argenti Apparatus · 2019-04 · Bicycles Stack Exchange · on “Upgrading From a 9 Speed Sora Derailleur?”
As a sort of addendum to Nathan Knutson's answer, focusing on things to do before replacing the derailleur. Make sure wheel is fully in the dropouts and parallel to the frame. Properly and clean the drivetrain with a degreaser and apply a bike chain specific lubricant, not penetrating oil such as WD-40, GT85 etc. There are many videos [LINK] that show how to do this. Check hanger alignment. From the photo it looks pretty good (cage should be parallel to the chainrings). It might be worth getting a bike store to check it with a hanger realignment tool. Replace cables and housings. Stretchy cables and sticky housings can cause the derailleur to not index properly. Run through a systematic dera
Recommends Argenti Apparatus · 2019-07 · Bicycles Stack Exchange · on “Shimano 105 R7000 drivetrain makes crackling sound”
It sounds like your derailleur indexing is bad. The 'crackle' is the chain trying to climb the shift ramps on the next largest sprocket then falling off. It may be that your derailleur indexing is badly adjusted. You can run through a rear derailleur adjustment process [this video] and see if this fixes the problem. You should also check that your derailleur is aligned properly. The derailleur hanger can get bent so that the derailleur cage is not longer parallel to the rear wheel. If you pick rear wheel of the bike up and look down the line of the chain you can see if the cage is grossly out of alignment if it is not parallel to the chainrings. A bike repair shop can check and re-align the hange
Recommends bradly · 2020-04 · Bicycles Stack Exchange · on “My bike shifting won’t surpass 6”
It sounds like your derailleur cable has a bit of slack in it. You will find this video useful, its easier to give you this link with a lot of good footage than try to explain it myself.
Recommends Jeff · 2020-06 · Bicycles Stack Exchange · on “Bottom jockey wheel on rear derailleur keeps skipping chain”
The first thing to be checked is the derailleur's hangar alignment. A bent or misaligned hangar can produce this effect on the derailleur jockey wheels. There is a special tool to check and correct this, though one can fashion a homemade device to do the trick. Park Tool's advice [LINK] on their derailleur hangar alignment tool. You intimated that you're using the limit screws to attempt to align the jockey wheels. This is only helpful on the two extremes of the cassette. The H limit screw should be set with the chain on the large chainwheel and smallest, outermost sprocket. The position of the upper jockey wheel of the rear derailleur should be aligned with the outside, vertical plane of th