Choose a replacement derailleur hanger for the actual frame and rear-axle arrangement, not just the name on the derailleur. The hanger must seat correctly against the dropout and provide the right derailleur attachment. A part that looks almost identical can still be wrong. Start with the original part number when available, then confirm it against the bicycle in front of you.
Start with the frame and the part you removed
Suppose the replacement listing names your bicycle, but its fastening holes differ from the broken hanger. That mismatch matters more than the listing. Production changes and previous repairs can leave you with a different part from the one a catalog suggests.
Keep the old hanger, including broken pieces, until the replacement is confirmed. Photograph both faces, any stamped numbers, and the frame attachment area. Take the pictures straight on, with enough light to show the locating surfaces rather than just the derailleur hanging below them.
Also record the bicycle's exact version, approximate purchase year, frame serial number, and whether its rear wheel or axle arrangement has changed. Those details give a seller something concrete to check. A photograph of the whole bike alone rarely shows the differences that decide the fit.
Reject a near match before ordering
Compare the candidate with the original at the places where it actually attaches:
- Axle interface: the opening and any axle-related threads must suit the existing arrangement.
- Frame seat: check the locating shape and whether the hanger sits inside or outside the dropout.
- Fasteners: match their positions, number, and required threads, not merely the size of the screw heads.
- Derailleur connection: confirm the intended mounting arrangement as well as the frame fit.
If one of those differs, set that candidate aside. Do not file a locating edge, enlarge a hole, or add washers to make it sit approximately where the old one did. You would be changing the attachment instead of replacing the correct part.
Photos are useful for rejecting obvious mismatches, but hidden dimensions can remain uncertain. When two candidates still look alike, ask for confirmation of the exact part number rather than choosing the closest-looking one.
Confirm the part number, then check the repair
Send the photos and bicycle details to the bicycle maker or replacement-parts supplier. Ask a specific question: does this part number fit this frame, axle arrangement, and derailleur attachment? Keep the answer with the purchase record so the next replacement is easier.
The correct hanger still needs proper installation and an alignment check. If shifting remains poor afterward, the shifter troubleshooting guide covers the wider diagnostic path; another random hanger is not the next test.
When comparing electric bikes, ask how replacement drivetrain parts are identified and supplied. An exact part reference is more useful during a repair than a promise that components are widely available.
