What causes a rear derailleur hanger to bend?

A common cause of a misaligned hanger is from the bike falling over to the right side. This pushes the derailleur body inward, bending the hanger. This is because there is very little stress from riding the bike or shifting gears. As a rule of thumb, if a hanger survives a repair by bending, it will survive use.

How do you straighten a bent mech hanger?

If you don’t have an alignment tool, you can make do with a large adjustable spanner. Tighten the spanner over the hanger so that it covers the threaded hole and clamps the hanger snugly. Then twist the spanner gently until the hanger is back in line.

How can you tell if a mech hanger is bent?

Rotate the arm of the alignment tool to the 12 o’clock position (pointing straight up). If your hanger is straight, the gauge arm should sit in the same position relative to the rim. If it’s not straight, this will indicate the direction in which the hanger is bent.

Can you fix a bent derailleur hanger?

If the surface of the hanger is visibly fatigued, or it’s so twisted as to be noticeable even without looking closely, it’s time for a replacement. However, a slightly misaligned hanger doesn’t need to be replaced, it can simply be straightened.

What is a rear mech hanger on a bike?

About Rear Mech Derailleur Hangers. A rear mech hanger is a sacrificial component part of a bicycle, designed to deliberately bend or break in order to limit or prevent damage to the bike frame and the other component parts of its drivetrain, when under duress.

How do you fix a bent rear derailleur hanger?

First judge how you believe the hanger to be bent. Then take hold of the upper part of the derailleur with both hands, cupping it right around the back to give the derailleur as much support as possible, so as not to damage it. Use reasonable force to yank it back towards straight.

How do you bend a hanger without breaking it?

Simply dial down the jaws of the spanner onto the end of the hanger and then it can be used as a lever to bend the hanger. Again, go carefully, and as this is not an exact science aim for something that looks ok by eye, and leave it at that.

How do you fix a bent cassette hanger?

Check the hanger looks straight, by eye. Avoid over-correcting the bend because this will weaken the hanger. Reinstall the mech, shift into the middle of the cassette and check the alignment again, as in step one. If the hanger still isn’t straight, remove the mech and try again.