How To Replace A Broken B-Link On A SRAM Derailleur

A broken B-link can leave a SRAM rear derailleur hanging at an odd angle, unable to shift reliably or vulnerable to further damage. The B-link is the small bracket and pivot connection that joins the derailleur body to the rear derailleur hanger. When its axle, bolt, threads, or surrounding plate fails, replacing the damaged assembly is usually safer than trying to straighten or reuse cracked hardware.

This repair is manageable for a home mechanic with a clean work area and the correct replacement part. SRAM has used several B-link designs across road, gravel, mountain bike, and electronic groupsets, so identification matters. A part for an older X9 derailleur may not suit an Eagle model, while newer direct-mount systems may use a different interface altogether.

Identify The Failed B-Link

First, shift the chain onto the smallest rear sprocket and inspect the derailleur from behind the bicycle. The derailleur should sit squarely beneath the cassette, with the upper jockey wheel aligned reasonably close to the sprockets. If the derailleur body swings loosely at the hanger connection, the B-link pivot or its retaining hardware may be broken.

Look for a snapped axle, missing washer, stripped thread, cracked B-link plate, or damage around the derailleur hanger. A bent hanger can look like a failed bracket because it also changes the derailleur angle. Remove the derailleur and inspect both parts before ordering anything. If the hanger is bent, replacing only the B-link will not restore accurate shifting.

The model name and generation are normally printed on the derailleur cage or outer body. Record whether it is a SRAM road, gravel, MTB, 1x, or 2x derailleur, and whether it uses a standard hanger or a direct-mount arrangement. Photographs of the broken joint can help a local bike shop match the correct B-link kit.

Gather The Correct Parts And Tools

Use a genuine SRAM replacement where available, or a reputable compatible kit that specifically lists your derailleur model. A complete kit may include the B-link, pivot axle, bolt, circlip, spacers, washers, and a small return spring. Do not assume the old washers and spring can be reused if they are scored, distorted, or corroded.

You will generally need a bicycle workstand, 4 mm and 5 mm hex keys, a torque wrench with suitable bits, degreaser, a small pick or flat screwdriver, and waterproof bicycle grease. Some designs use a Torx fastener or a different hex size, so check the SRAM service documentation before putting a tool into the bolt head.

Useful items for the repair include:

Avoid forcing a rounded fastener. A damaged tool interface can turn a straightforward repair into a component replacement, especially when a seized bolt is bonded by dirt or corrosion.

Remove The Derailleur Safely

Shift to the smallest cassette sprocket and release cable tension if the derailleur is mechanical. On a 1x drivetrain, this position gives the derailleur more room to move and makes it easier to reinstall the chain. If the chain is under heavy tension, hold the derailleur cage forward while removing the chain from the chainring, or use a quick link tool if the chain needs to come off completely.

Unbolt the derailleur from the hanger while supporting its weight. Keep any washers, spacers, or spring components in their original order, even if you intend to replace them. On some SRAM designs, the B-link bolt and the derailleur mounting bolt are easy to confuse, and mixing them up during reassembly can damage the threads.

Once removed, clean the hanger face and examine its threads. A hanger with pulled threads, a visible crack, or a mounting face that is no longer flat should be replaced. Do not clamp the carbon frame in a way that transfers force through the derailleur hanger, and do not use the derailleur as a lever to bend the hanger back into position.

Replace The Bracket Axle

Compare the new B-link with the old one before fitting it. Check the orientation of the stop, spring, spacer, and pivot surfaces. Take a quick photograph before dismantling the old assembly if the hardware is still partly intact. The B-link must sit in the correct direction for the derailleur body to rotate and for the spring tension to work properly.

Clean the pivot area and apply a thin film of grease to the axle or bearing surface. Do not pack grease into the clutch mechanism or contaminate the derailleur’s sealed electronic parts. Slide the components together in the same order as the original assembly, then start the fastener by hand for several turns.

The B-link should rotate smoothly without side-to-side play. If it binds before the fastener reaches its seated position, stop and check for a reversed washer, misplaced spacer, damaged thread, or incorrectly positioned spring. Tightening a misassembled joint can crush the bracket or lock the derailleur body in place.

Use the torque value specified for the exact SRAM model. There is no universal B-link torque that safely covers every generation. Tighten gradually with a torque wrench, keeping the bracket aligned with the hanger. If the replacement kit includes a new retaining clip or bolt, use it rather than transferring questionable old hardware.

Refit The Derailleur And Hanger

Before mounting the derailleur, verify that the hanger is fully seated against the frame and that its retaining bolt is secure. On many Australian bikes, replacement hangers are readily available through independent shops and online retailers, but model matching can be difficult when a frame has several similar-looking hanger shapes. The frame manufacturer’s part number is more reliable than a visual guess.

Thread the derailleur mounting bolt into the hanger by hand. It should turn smoothly without cross-threading. Keep the derailleur supported while tightening, and ensure the B-link stop contacts the correct part of the hanger or mounting interface. The derailleur should sit firmly with no obvious rocking, while the cage and jockey wheels remain free to move.

Reconnect the chain and shift cable if they were removed. If the cable end has frayed or the housing has been pulled sharply, replace the damaged section before adjustment. A new B-link cannot compensate for a cable that drags inside contaminated housing.

This is a useful time to inspect the rear wheel, axle seating, and brake clearance. The same visual check can be paired with the wheel and brake guides, particularly if the original impact involved a crash, pothole, or wheel removal problem.

Align And Adjust The Drivetrain

With the derailleur installed, check alignment from behind the bicycle. The upper jockey wheel should track beneath the cassette rather than sitting noticeably inboard or outboard. If it does not, inspect the hanger before touching the limit screws. A bent hanger must be corrected with a proper alignment tool or replaced; adjusting the derailleur limits only hides the underlying fault.

Set the high-limit screw so the upper jockey wheel lines up with the smallest sprocket. Add cable tension gradually and shift through the cassette. Then set the low-limit screw so the chain reaches the largest sprocket without being pushed into the spokes. Turn each adjustment in small increments and pedal the drivetrain while shifting.

Set the B-tension adjustment according to the derailleur’s instructions and cassette size. Many newer SRAM MTB derailleurs use a chain gap guide or a marked setup position. If the guide is unavailable, begin with the manufacturer’s stated position rather than guessing from an older derailleur. An incorrect gap can cause slow shifts, noise, or poor shifting under load.

Mechanical SRAM systems may need a fresh cable tension adjustment after the derailleur has been disturbed. Electronic AXS systems require a charged battery, correct pairing, and the appropriate micro-adjust procedure. Do not repeatedly operate the shift buttons while the chain is stationary under tension, as the motor may attempt a shift that cannot complete.

Test The Repair Before Riding

Perform a stationary test in a workstand first. Turn the cranks by hand and shift across the cassette in both directions. Listen for scraping, clicking, or delayed movement, and watch for the chain trying to overshift beyond either sprocket. Test the derailleur in several gears while applying light hand pressure to the pedals.

Before leaving the driveway, complete these checks:

Take a short test ride on a quiet street rather than heading straight into a long climb or busy commute. In Melbourne or Sydney, a few minutes of stop-start riding can reveal cable tension problems quickly, while a Brisbane summer shower may expose contamination that was not obvious in the workshop. Avoid shifting under maximum sprinting force until the repair has proved reliable.

After the ride, inspect the B-link again. A new clicking sound, visible movement, or sudden loss of indexing indicates that the repair needs further investigation. Stop riding if the derailleur can move into the spokes, since that can damage the wheel, cassette, chain, and frame.

Prevent Another Derailleur Failure

The B-link is often damaged by an impact rather than ordinary wear. A fallen bike, a branch caught in the wheel, a rock strike on a mountain trail, or a derailleur forced into the spokes can bend the hanger and overload the bracket. Check the complete rear derailleur assembly after any crash, not only the visibly broken component.

Keep the chain clean and lubricated so the derailleur does not carry unnecessary resistance. Inspect the jockey wheels, cage plates, and clutch area during routine drivetrain cleaning. Riders in coastal areas such as Perth, Adelaide, or the Queensland coast should pay attention to salt and moisture around fasteners, while wet-weather commuters should dry the drivetrain after regular rain.

A few habits reduce the chance of a repeat failure:

Parts availability can vary between Australian retailers, and express shipping may not help when a particular SRAM generation is obsolete. Recording the derailleur model, hanger part number, and B-link specification in your maintenance notes makes future repairs faster. A workshop can also confirm compatibility before you spend money on a kit that fits a similar-looking but different derailleur.

A correctly installed B-link restores the derailleur’s mounting position, but accurate shifting depends on the hanger, cable system, limits, chain gap, and cassette all working together. Take time to inspect those related parts, use the correct torque information, and test every gear before returning to traffic or technical trails. If the bracket broke during an impact, have the complete rear end checked by a qualified bike mechanic and replace any part that remains bent, cracked, or loose.