Important Alignment Note
There are some bicycle dropout designs
that do not allow correction by bending, or cold-setting. Extremely
extremely thick dropouts typically cannot be bent. Other examples include
most suspension forks, most titanium frames, and oversized dropouts for
the 14mm "freestyle/bmx" axles.
When a dropout is bent for correction, the frame tubing does not bend.
Additionally, the dropout face does not bend. What is being bent is the
narrow section between frame and dropout. If there is not a narrow section
between the frame and dropout, it may not be repairable. Without this
"neck", you are attempting to bend the frame tube.
Additionally, dropouts that are bonded into the frame, such as on
carbon fiber frames, may not be repairable. Consult with the manufacturer
if in doubt. However, even if the bicycle design will not allow
correction, it is useful knowledge to inspect dropout alignment.
An example of non-repairable bonded dropouts in a carbon fork.
Once dropouts are aligned, they tend not require constant re-checking.
When the hub is clamped in place, the system is quite strong. Even extreme
riding and smashing the wheel is unlikely to bend the dropouts.
Procedure for Dropout Alignment
- Rear dropouts with centering screws: First, install dished wheel
in frame, and pull axle to screws. Check that wheel is centered,
adjust screws as necessary.
- For the rear, slide spacer to inside of dropouts. For front, slide
wide spacer to outside of dropouts.
- Pull FFG-1 fully up into dropout. Hold threaded shaft and secure
T-handle clockwise firmly against dropout. If tool begins to move,
stop securing, tool is tight enough.
- Adjust bushings until there is a slight gap between them. Move
threaded bushings side to side until gap is centered in
dropouts.
- View FFG-1 from all directions for any offset between bushings.
Error may also be felt by running a finger across the gap.
An example of parallel but offset dropouts. Move left side upward and right side downward.
Begin by moving left dropout upward.
- To correct by bending, grab bushing with one hand, and handle with
other. Bend by moving hands opposite directions. If in doubt as to
which side to bend, flex gently and note movement of bushing before
proceeding to bend.
- Correct offset until bushing cylinders show no error greater than 0.5mm.
- View bushings for any gap opening that is not parallel to face of
bushing. Correct by bending dropout. Again, if in doubt in choosing
one side, flex handle and note movement of bushing. If largest gap is
less the 0.5mm, drop outs are adequately aligned.
See also related article,
Frame Alignment..
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