48. How to Align a Rear Derailleur Hanger
Derailleur hangers are easily bent and can cause shifting problems.
50% of the cost of the bicycle featured in this video was donated by JensonUSA.
Today we’ll learn how to straighten integrated derailleur hangers. Shifting problems caused by a bent derailleur hanger are quite common. This can happen if your bike is dropped, crashed or bumped, or if it was poorly aligned at the manufacturer. The result is poor shifting even after all other adjustments have been made.
For this job you’ll need a repair stand and a hanger alignment gauge like this one called the DAG-2 from Park Tool. It costs about $50 dollars. When compared to bike shop labor charges, it will pay for itself after 3-4 uses. You’ll also need a 5mm hex key for the derailleur mounting bolt, and a string or small strap to hold the derailleur out of the way while you align the hanger.
It is important to make sure your rear wheel is true and properly mounted in the frame dropouts, as the alignment tool compares the derailleur hanger to the rim surface. See the tutorials titled How to Remove and Install Your Wheels and How to True a Wheel.
The first step is to shift the rear derailleur onto the smallest sprocket and then remove the rear derailleur by turning the mounting bolt all the way counter-clockwise. There is no need to remove the shift cable or chain. Then tie the derailleur up onto the frame to keep it out of the way. If you have a replaceable derailleur hanger, you’ll first want to make sure the bolts holding it in place are properly tightened so they don’t move.
Now thread the tool’s shaft all the way into the hanger threads by turning it carefully clockwise into where the derailleur was mounted. If it doesn’t thread in smoothly, the threads may be damaged and need to be chased with a tap. We’ll cover this in a future tutorial. Do not use the tool’s threads as a thread chaser.
We’ll be checking the alignment at four different places on the rim: the 9 o’clock and 3 o’clock for horizontal alignment, and the 12 o’clock and 6 o’clock for vertical alignment. When aligned correctly, the alignment tool's indicator will be roughly the same distance from the rim at all four locations.
For horizontal alignment, move the alignment tool’s arm to the 9 o’clock position and rotate the wheel so the valve is at the same spot. Loosen the knob and slide the indicator so it contacts the outside edge of the rim, and then tighten the knob again to hold the indicator in place. Now rotate the tool arm and valve around to the 3 o’clock position and see where the indicator sits. If the tip of the indicator is within 4mm of the rim on this side then the horizontal alignment is ok. If the difference is more or less than 4mm, carefully pull or push the tool’s arm, using it as a lever to slightly bend the hanger in the right direction, and then re-check the alignment on both sides.
You may need to repeat this process a few times until the alignment is within range. It’s important not to bend the hanger too much with the alignment tool. It’s best to bend it a little bit and then have to bend it some more, rather than bending it too much and having to bend it back again.
For vertical alignment, keep the indicator in the same position and then check the 12 o’clock and 6 o’clock positions the same way we did for the horizontal alignment. Always remember to move the air valve along with the indicator and place the indicator at the outside edge of the rim.
Once the hanger is aligned and within 4mm both horizontally and vertically, unthread the alignment tool. Apply a little waterproof grease to the derailleur's mounting bolts threads and begin threading it back in clockwise. Make sure the B-screw adjustment is sitting behind the derailleur hanger. Then tighten the derailleur to the specified torque, usually around 8-10 Newton Meters or 70-90 Inch Pounds.
Hi - my bike won't shift into the big chain ring up front when in the 4 or 5 biggest cogs in the back. In the smaller cogs in back, it shifts ok up front. Any thoughts or suggestions as to what's going on, and how to fix, would be greatly appreciated.
Thanks!... Read more >>
I just finished a complete overhaul if the bike. Everything was cleaned, bearings washed and packed in fresh grease.
When I went to live the chain, I noticed that back pedalling causes the chain to stick:
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Hi, first post, very noobie to bike stuff sorry
(Sorry, it's a little long, tried to keep it concise, sry).
Basically, when the bike is on a stand or even just picking the bike to rear tire is hovering, when pedaling and shifting through the front gears 1,2,3 it shits perfectly. Very smooth and fluid. However, when I'm riding the bike the bike gears will not shift at all!
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My front derailleur is a "Falcon" ---never heard of them! My problem is that I can shift to my large chainring or sprocket but as soon as I let go of the shift lever the derailleur pops the chain right back onto the small ring. W Thanks for your assistance.hen I move the shift lever it "clicks" several times---could there be some type of ratchet that is broken?... Read more >>
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Hi guys -- I'm new to the forum. Thanks for reading.
I'm fixing up a bike I've had for ~15 years that, sadly, I wasn't able to maintain. The bike is an 18-speed Royce Union mountain bike. Aside from new tubes/tires and a new chain, everything else is original (thumb shifters, both derailleurs are Shimano).
The original chain was just too rusted, so I replaced it, and it runs nicely now. Almost. It's fine on the granny chainring, and it's fine on the big ring, but when it's on the middle ring (the one that I tend to use the most), the chain drags across the inside... Read more >>
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My rear derailleur is horizontal to the bike frame as opposed to vertical.
I can see no obvious reason for this and am unsure of how to fix it.
The bike was shifting just fine until I literally put it down, picked it back up and went to take off and the rear derailleur had the before mentioned issue.
Any help would be much appreciated.... Read more >>
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I followed the instructions in this video
but I still have the same problem on a Shimano Sora race bike.
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Any hint?... Read more >>
I have an old 1984 Miyata Model 100
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I have one of these old STI shifters from the early 90's
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The button goes all the way without resistance.
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Thanks in advance!... Read more >>