Hanger Alignment

[Dirtbreath]

So I am trying to troubleshoot some shifting problems. I have replaced my derailleur hanger but am not sure the old one was bent.

 

I dont have a hanger alignment tool and frankly cant justify the cost of one either. Was wondering if its possible to check the alignment of the hanger against the face of the non-drive dropout. Place a square on the inner face of the other dropout and compare the distance between the dropout and the extremity of the hanger.

 

Any reason why this would be an inaccurate measurement?

 

[de la mac]

Go to a bike shop

 

[droo]

The longer the lever, the more accurate your measurement's gonna be. Take it to the bike shop - they won't charge you much (if anything) to sort it out, and it's a 2 minute job.

[Johan Bornman]

A quick check is to put the bike in a stand. Stand behind and look at the back dropouts. Now undo the QR and watch for movement at the dropout. Usually a dodgy drop-out makes the jockey move as the QR is tightened. This is not a perfect method since a drop-out can be bent in parts where the clamping wheel will not move it, but it is a start.

[Dirtbreath]

So I put a square on the non drive dropout and checked the distance at the dropout and at the end of the hanger. 100%. Gears working perfectly in the stand but will check tomorrow after a ride. Took me about 2 minutes. Lot less hassle than going to a bike shop. Also want something that can be done out on trail/camp.

 

Hopefully I dont eat my words.

 

Johan, not sure if I understand your method. If the dropout is square but the hanger is bent, how would tightening the skewer move the jockey wheels?

 

[Johan Bornman]

If the hanger is out of alignment and you close the QR, two things happen:

 

1) The wheel with its perpendicular jamb nut forces the hanger towards 90 degrees and;

2) The out-of-alignment hanger forces the jamb nut to bend the wheel's axle.

 

You can see the movement of the two components as you close the QR.

 

If the hanger moves, the jockey moves and it is highly visible due to the fact that its movement is amplified due to the length of the lever.

 

 

 

[Dirtbreath]

I'm still not clear here. If the hanger is bent, it will be bent along the length below the dropout. Will the dropout not still be square? If you tighten the skewer it should not affect the hanger as the damage is below the area where the jamb nut is compressing the dropout.

[Johan Bornman]

The bend is never localised and stretches into the drop-out part of the hanger too. The alu is too hard for such a localised bend and, you'll notice that the attachment screw/s are always slightly upwards, leaving space for a bend to go up.

 

Try it, you'll see.

[Dirtbreath]

Makes sense then.