Everything you need to know about a bike's derailleur hanger

Common problems and solutions

Is it important to remember that to avoid unpleasant surprises during your training, checking the condition of the derailleur hanger must be done before each outing (in the same way as the pressure of the derailleur hangers). tires, the condition of the frame but also the wear of the cartridges or pads of your brakes...)?

During a daily check you simply need to check that the leg is perfectly in line with your frame.

While riding, gears that have difficulty shifting are not necessarily the sign of a poorly adjusted derailleur but can also indicate a derailleur hanger about to give way. In fact, your derailleur may receive an impact during transport, a fall with other cyclists or even a simple fall from your stationary bike (in mountain biking, branches or brambles can also cause breakage of the frame tab).

The derailleur hanger is broken

If it is a modern leg, independent of the frame, simply dismantle it and replace it. There are many models (hundreds...) so unless you have a very classic bike or extraordinary luck, you will certainly have to order the part, which will immobilize the bike. ©lo for a little while. A derailleur hanger costs on average €10. If a bracket cannot be found, it is possible to use a similar one and adapt it slightly to make it fit on the frame.

The thread of the derailleur hanger is torn off

If the screw thread is out of order, on a leg not attached to the frame, we replace the leg par a new one.

On a tab attached to the frame, there is an accessory allowing you to save the frame, it is the “Dropout saver” from “Wheels Manufacturing”. It costs a dozen euros and is available in two versions: wide and thin, depending on the thickness of the tab. It is a nut that fits in place of the original thread, with a hexagonal shape on the other side, allowing the derailleur to be tightened without rotating the nut. . You then have to re-drill the hole with a 12mm drill bit and put the nut in the hole, then hold it with a wrench while you screw in the derailleur.

The derailleur hanger is warped/twisted

It happens that the derailleur hanger becomes warped for several reasons (natural wear, impact, chain getting stuck in the derailleur and twisting it). This is easy to fix as long as you have the right tools and the bracket is made of steel. If it is made of aluminum, you can attempt a repair but it is likely that the tab will split, the aluminum bending poorly, you will then have to check its condition carefully to avoid leaving with it again. a weakened leg.

For repair, you must use a derailleur hanger alignment gauge (or a derailleur hanger straightener for short), this tool is made up of a threaded rod similar to the screw of a derailleur, it must be screwed onto the hanger as if it were a derailleur. The long handle of the tool is used to visualize the veil more easily par in relation to the wheel and to use a lever arm in order to straighten it.

To correct an obvious veil, you must proceed little by little and not all at once at the risk of breaking the leg. The maneuver is simple, it involves twisting the tab (in the right direction obviously, you must not accentuate the veil) using the lever arm formed by the unveiler.

If the veil is weaker, we use the wheel-handle distance of the tool which must remain constant when we rotate the veiler. As long as it is not, we must continue to twist the leg, we proceed par groping, a bit like unraveling a wheel.

Remember to consult our video tutorial on replacing the derailleur hanger.