Rear derailleur not shifting right: how to adjust it

Find the cause by symptom

Shift through every gear on a stand while you turn the cranks, then note which of these you see. Work through the causes in the order given, because a bent hanger or worn chain will undo any cable adjustment.

Chain is slow to climb to bigger sprockets, or rattles against the next bigger sprocket

Cable tension. On Shimano, if the chain rubs the next larger sprocket, turn the barrel adjuster clockwise. On SRAM GX Eagle, slow shifts to bigger cogs mean too little tension: turn the barrel adjuster counter-clockwise one click at a time. See cable tension and indexing.

Chain is slow to drop to smaller sprockets

Too much cable tension. On SRAM GX Eagle, turn the barrel adjuster clockwise one click at a time. On Shimano, redo the indexing from the start (below), which backs the tension off in fixed clicks.

Chain falls off past the smallest sprocket or into the spokes

Limit screws. The high screw stops travel at the small end and the low screw stops it at the big end. See limit screws.

Chain will not reach the largest or smallest sprocket

A limit screw is set too tight, or cable tension is too far out. Check the limits first.

Cage hits the largest sprocket, or shifting is rough on the biggest cogs

B-tension is set too close. Shimano says to tighten the B-screw until the cage clears, then set it properly. See B-tension and chain gap.

Shifting will not settle no matter how you turn the barrel

Shimano lists three causes when adjustment is impossible: a bent hanger, a dirty or dry cable, and outer casing that is too long or too short. Also check for a gap between the stopper plate and the B-tension stop, which Shimano says makes shifting worse over time. See bent hanger and loose mounting.

Chain skips under load when you pedal hard

Usually a worn chain or cassette. SRAM's Transmission troubleshooting also lists a dirty drivetrain, chain gap too large and a chain that is too long. See worn chain.

Chain slaps the frame on rough ground (Shimano clutch derailleurs)

On RD-M6100-SGS and the CUES derailleurs with a stabilizer, the switch lever must be ON for riding. It is set to OFF only for setup. If it is ON and the chain still slaps, the clutch friction can be adjusted: see Deore clutch friction.

Ticking or grinding from the derailleur cage

Shimano says to replace a pulley that is noisy because it has play in it. Pulley steps are on each model page, for example Deore and GX Eagle.

Which guide is yours

The model number is printed on the derailleur. Find it in this table and use that page for torque values, part numbers and the full steps.

Eagle Transmission derailleurs bolt straight to the frame with no hanger and have no limit or B-tension screws, so most of this page does not apply to them. Skip to Eagle Transmission.

The adjustment order

Shimano and SRAM both set up a cable derailleur in roughly this order. If you only want to fix one symptom, you can start at the matching step, but if things are badly out, go from the top.

Before you start: keep fingers out of the chain and sprockets while you turn the cranks, and keep the wheel from turning while you clamp the cable and fit the end cap, as Shimano instructs.

1. Check the hanger is straight and the derailleur is tight on it, with no gap at the B-tension stop (Shimano) or behind the B-washer (SRAM). See hanger and mounting.

2. Check chain length. A chain that is too long or too short upsets B-tension and shifting. See the chain length page.

3. On Shimano clutch derailleurs (RD-M6100-SGS, CUES models with a switch lever), set the switch lever to OFF for adjustment.

4. Set the high limit screw on the smallest sprocket.

5. If you are fitting a new cable, set the shifter to its starting position, clamp the cable, and take up the initial stretch.

6. Set the low limit screw on the largest sprocket.

7. Set the B-tension screw (chain gap).

8. Set the indexing with the barrel adjuster.

9. Shift through every gear while pedaling, switch the clutch lever back to ON, and test ride.

Limit screws

The limit screws only stop the derailleur at each end of its travel. They do not change indexing in the middle of the cassette. On all the models below you look from behind the bike and line up the upper (guide) pulley with a sprocket.

On the 105 RD-R7100, Shimano says to tighten the B-screw a little before setting the low limit, so the guide pulley clears the largest sprocket. On Tiagra RD-4700, if the inner plate is close to the spokes, turn the low screw in further. SRAM says to recheck both limits after you set the chain gap. Steps: Deore high and low, 105, Tiagra, GX Eagle.

B-tension and chain gap

The B-tension screw (Shimano also calls it the end adjust bolt, SRAM calls it the B-adjust screw) sets how close the upper pulley sits to the big sprockets. Too close and the cage hits the sprockets or shifts roughly. Too far and shifts on the big sprockets get slow. This is where Shimano and SRAM differ most.

Two points catch people out. SRAM measures on the second-largest cog with the suspension at sag, while Shimano measures on the largest sprocket. And the older SRAM gauge 11.7518.082.000 is discontinued and does not fit 52T cassettes; SRAM says to use 11.7518.099.000, which works on 10-50 and 10-52 Eagle. For CUES RD-U3020 to RD-U8020 with other cassettes, check the table in DM-LARD003.

Redo the B-tension whenever you change the cassette tooth count. Shimano also notes that on some frames the B-screw is used to keep the derailleur off the chainstay, and on 105 with a UDH hanger, to take up chain slack. Steps: Deore, 105, GX Eagle chain gap.

Cable tension and indexing

Indexing is the cable tension that puts the derailleur exactly under each sprocket when you click the shifter. Shimano uses a fixed method that ends with a set number of clicks. SRAM GX Eagle is adjusted one click at a time by symptom.

Shimano Deore, 105 and CUES

1. Set the clutch switch lever to OFF if your derailleur has one.

2. Shift to a sprocket 5 to 7 steps from the largest (Deore and CUES), or the fifth sprocket from the largest (105). On a double, use the big chainring.

3. If the chain already rubs the next larger sprocket, turn the barrel adjuster clockwise until it goes quiet.

4. While pedaling, turn the barrel adjuster counterclockwise until the chain just starts to rub the next larger sprocket.

5. Turn the barrel adjuster 5 clicks clockwise (3 clicks on CUES RD-U2000). That is the setting.

6. Shift through every gear while pedaling and listen for noise. If it is noisy, start again from step 2. Switch the clutch lever back to ON and test ride.

   From DM-MARD001, DM-RARD011 and DM-LARD002, SIS adjustment

Shimano Tiagra RD-4700

Tiagra uses a different check on the second sprocket: push the shift lever just far enough to take up its free play without shifting, and turn the crank. The right setting is when the chain touches the third sprocket and makes a noise at that point, then goes quiet when you let go of the lever. Full steps are on the Tiagra 4700 page.

SRAM GX Eagle

• Slow shifts from a larger to a smaller cog: turn the shifter barrel adjuster clockwise, one click at a time, until it shifts cleanly.
• Slow shifts from a smaller to a larger cog: turn it counter-clockwise, one click at a time.

If the barrel adjuster runs out of travel, reset the cable: shift to the smallest cog, turn the barrel adjuster clockwise to its stop and back one full turn, then pull the cable tight and clamp it at 4.5 N·m (40 in-lb). Full steps: GX Eagle cable routing and indexing.

When a new cable is going in

Set the shifter to its starting position first. On Deore M6100 press the release lever 11 or more times. On CUES press it 10 or more times for 11-speed, 9 or more for 10-speed, 8 or more for 9-speed. On 105, Shimano's derailleur manual says 11 or more and the ST-R7120 lever manual says 10 or more. On Tiagra ST-4700 press it 10 or more times. Then clamp the cable, hold the derailleur still and work the shifter several times to seat the cable and housing, and clamp it again while pulling it tight. Shimano's cable fixing bolt torque is 6–7 N·m on all these models. Cable steps: Deore, 105, Tiagra, GX Eagle.

Bent hanger and loose mounting

A bent hanger tilts the derailleur so it can never line up with every sprocket at once. Shimano's manuals for Deore M6100, 105 R7100 and CUES all say to check the hanger with Shimano's TL-RD11 before anything else. SRAM's GX Eagle manual says to check it with a derailleur hanger alignment tool. If you do not have one, a bike shop can check and straighten the hanger.

1. Check the hanger with the alignment tool and straighten it if needed.

2. Shimano: thread the derailleur bolt in straight, not at an angle, so the stopper plate sits against the B-tension stop with no gap. Recheck this from time to time; Shimano says a gap opening up here makes shifting worse.

3. SRAM GX Eagle: push the B-adjust washer forward as you fit the derailleur so there is no gap between the B-washer and the hanger. SRAM warns that a gap can let the derailleur loosen or break away. Do not grease the bolt or hanger threads.

4. Tighten the mounting bolt with a torque wrench to the figure for your model (table below).

On Tiagra RD-4700, use a straight hex key pushed fully into the bolt, not a ball-end key, which Shimano says can strip the hole. Also check the B-tension bolt does not catch on the dropout tab and bend as you tighten.

Worn chain

A worn chain can skip under load, and no derailleur adjustment fixes that.

• SRAM GX Eagle and Eagle Transmission: SRAM says to replace the chain at 0.8% elongation. For GX Eagle, measure with the SRAM Chain Wear Indicator; for Transmission, SRAM says to use a SRAM-qualified checker.
• Shimano: Shimano's chain manual says to inspect the chain for bent or cracked links and for skipping, and to clean it with a neutral detergent, never an acid or alkaline cleaner such as a rust remover.
• SRAM's Transmission troubleshooting says that when nothing else explains poor shifting after heavy use, replace the chainring, chain and cassette together.

A new chain has to be the right length. See the chain length page. On Eagle Transmission, a new chain also means redoing the full derailleur setup.

SRAM Eagle Transmission is different

Eagle Transmission derailleurs (AXS models and the cable-operated Eagle 90 RD-90-A1 and Eagle 70 RD-70-A1) mount straight to frames built to SRAM's UDH standard, with no separate hanger to bend. SRAM states there are no adjustment screws in the system: no high or low limit screws and no B-screw. The gap is set at installation by the Setup Key position and the Setup Cog, then the mount bolt is tightened to 35 N·m while you pull the cage back.

If Transmission shifting is off, SRAM's list of things to check is: rear axle not torqued, mount bolt not at 35 N·m, a dirty or dry drivetrain, cassette not at 40 N·m, chain gap too large, and a worn chain, cassette or upper pulley. The fix for a wrong gap is to redo the installation on the Setup Cog. Fine tuning is MicroAdjust on AXS models, or the barrel adjuster on Eagle 90 and Eagle 70. SRAM also notes that a full-suspension bike hanging fully extended in a stand can shift roughly and still be fine at sag. Steps: install, MicroAdjust, Eagle 90 and 70 cable setup.

Related: Chain length, Shimano Deore M6100, Shimano 105 R7100, Shimano CUES, SRAM GX Eagle, SRAM Eagle Transmission