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There are many crucial parts of a bike, like the derailleur hanger. It keeps the rear derailleur perfectly aligned with the cassette cogs. And it’s made to bend or break on impact. If the hanger isn’t bent too badly, you can straighten it out. Then you don’t have to replace it!
Purpose of a Derailleur Hanger
The derailleur hanger connects the rear derailleur to the frame. It absorb impacts that would otherwise badly affect your frame. When it’s out of alignment, the derailleur pulley is also misaligned with the cassette cog. In turn you can’t shift properly. A hanger that’s too far bent can make the derailleur shift the chain into the spokes. This could damage the derailleur and the wheel. Which means much more expensive repairs.
How to Straighten a Bent Derailleur Hanger
1. Get a hex wrench and a derailleur hanger alignment tool.
2. Make sure the back wheel is installed correctly. Shift the chain into the smallest cog to remove the rear derailleur. Unscrew it from the hanger with a hex wrench and turning counterclockwise. Hold the derailleur as you’re doing this to keep it from springing back.
3. Lightly grease the threads of the alignment tool and install it into the hanger threads. Turn the arm until it points straight down in the 6 o’clock position. Maneuver the gauge until it lightly touches the rim.
4. Turn the arm of the tool until it points straight up in the 12 o’clock position. A gap between the tool and the rim means the hanger is bent in. No gap means it’s bent out.
5. Turn it to the left in the 9 o’clock position then to the right in the 3 o’clock position. Gaps in these spots mean the hanger is bent in a second position, like inboard or outboard.
6. For horizontal or vertical alignment, push or pull on the tool to bend the hanger in the required direction. Go little by little while rechecking to make sure it’s moving the hanger how you want it to.
7. Turn the gauge all the way around the rim to make sure it follows the arc. Remove the tool and reinstall the derailleur.
8. Adjust your gears to make sure they’re shifting properly. If they are, you’ll know the hanger is back in place.
How to Replace a Broken Derailleur Hanger
1. Get a hex wrench and a new hanger.
2. Remove the back wheel, rear derailleur, and broken derailleur hanger.
3. Apply grease, anti-seize, or threadlocker to the bolt if it’s recommended by the manufacturer.
4. Install the new hanger. If it uses more than one fastener, tighten the bolts evenly to the recommended torque.
5. Reinstall the back wheel and check the alignment of the new hanger.
6. Reinstall the rear derailleur and check the gears to make sure they’re shifting properly.
Get Your Bike Serviced at Our Shop in Scottsdale
These instructions will help you fix or replace a bent derailleur hanger on your own. But there may be a time when you need professional service. Get it here at Airpark Bike Co in Scottsdale, AZ. We can handle any and all cycling repairs. Getting your trusted riding companion back to you in top shape in no time! Call us or stop in now to set it up.