• Park Repair Stand
• Park DAG-1 Derailleur Alignment Gauge
• Hex wrenches as needed.

• Front derailleur - limit screws and index settings.
• Rear derailleur - limit screws and index settings.
• Rear derailleur - overhaul.
• Rear derailleur - bent hanger.
• Wire cable-sizing and cutting inner wire cable and housing (gear and brake).

A mis aligned derailleur hanger will often result in poor shifting performance. A common cause of a mis aligned hanger is from the bike falling over to the right side. This pushes the derailleur body inward, bending the hanger.

It is often possible to repeatedly re-bend many derailleur hangers. 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. However, there are some hangers that do not repair well. Extremely thick hangers and titanium hangers are difficult and sometimes impossible to repair. Bolt-on type hangers that are replaceable are align able. However, these types of hangers can be tricky to align if the clamping design of the hanger to the frame is less than adequate It is common for these type of replaceable hanger to move in the mount.

After aligning and correcting the derailleur hanger, it will be necessary to check all rear derailleur adjustment, including limit screw and index settings. For rear derailleur adjustments see Rear Derailleur Adjustment.

Note: Newer DAG-1 models will now come with 2 o-rings for the slider. These will help prevent slider from falling out and can be used as markers when racks or fenders prevent full DAG-1 rotation. This procedure will be described at the end of this article.

Begin by mounting the bike in a repair stand with the wheels level as the bike would appear on flat ground. Check that the rear wheel that is mounted straight in the frame. The wheel does not need to be dished or true for use of the tool. Remove rear derailleur. Install DAG-1 and tighten handle. NOTE: Do not use the DAG-1 threads as a "chaser" of bad derailleur hanger threads. Chase and clean the threads using the Park Tool 10 x 1mm, TAP-10.

Rotate the arm toward the left side of rim, at the "9:00 o'clock" position. Rotate the tire valve to the 9:00 position. Use this point on the rim as a constant reference when checking the hanger. By checking the same point on the rim, wheel trueness or dish will not affect alignment.

Loosen the sliding gauger knob and move the sliding gauge to contact rim and secure knob.

Slide gauge bracket towards hub before rotating arm. This prevents gauge from begin forced against rim.

Rotate DAG-1 and rotate rim valve 180 degrees to the 3:00 position. Slide indicator toward rim to same point near valve.

There are three possible results.

• Condition A: The gauge is barely touching the rim. In this case the hanger is aligned horizontally.

  

• Condition B: The pointer is away from the rim some distance. The hanger is mis aligned.

  

• Condition C: The pointer strikes inside the rim, indicating a mis aligned hanger.

  

  It is easier to determine the error by seeing the gap between rim and gauge. In condition B, re-set tool at the 9:00 position and rotate back to the 3:00 position. There will be a gap between rim and gauge.

When bending hanger, it is best to bend small in amounts and re-check. The amount of error is actually one-half the gap between gauge and rim. As the gap is closed, it increases at the reference point 180 degrees away. Bend a bit, re-check both side, and then re-bend a bit more. Generally, it is best by having the DAG-1 arm next to the chain stay. This allows you to use the stay for leverage and control the amount of bending either inward or out. Repeat bending and checking until the gap is less then 4mm. Use a 4mm hex wrench as a "go-no go" gauge.

After getting the horizontal aligned, check and aligned, move on to check the 6:00 and 12:00 position. Set gauge to 6:00 position, then check at 12:00 position.

Again, bend only one-half the amount of gap. Reset pointer at each bending of hanger. When gap is less then 4mm, keep same the setting and check 3:00 position. If three points 90 degrees apart are within 4mm, hanger is aligned. Continue aligning as necessary.

Push outer o-ring to slider. This marks the position of the gauge relative to the slider.

When the gauge cannot pass by a frame stay, fender stay, or rack, loosen gauge knob and pull gauge back to clear.

Return the gauge so the o-ring is back in the original position. In the image below, the gauge is contacting the rim, but the o-ring is positioned away from the slider. In this situation, the gauge would be resting inside the rim. There will be situations where the o-ring contacts the slider, but there will be a gap between rim and gauge end.