DIY dropout alignment

[[email protected]]

Today I aligned the rear dropouts on a beater bike, that someone had
pinched together trying to install a too-narrow hub using skewer
pressure. Well, the skewer snapped, and when a suitably spaced hub was
found later it didn't want to seat properly, tightening one axle nut
caused the wheel to go way off kilter. I knew that I knew how to align
dropouts, so I turned to my second memory (the internet) to retrieve
the information. I found the park tools website:
http://www.parktool.com/repair_help/FFG.shtml which illustrated
excellently how to accomplish what I needed to do with a tool I didn't
intend to buy.

I had a pretty good idea how I was going to accomplish this, but since
I love the internet so much I searched for existing DIY efforts
anyway. I was a little surprised to read this discouraging note from
the late great Sheldon Brown: "There's no easy "home-mechanic" tool
for fork end alignment, except for a big adjustable wrench and a good
eye. I would advise, if in doubt about the alignment, that you take it
to a shop for this purpose, even if you do the frame spreading
yourself." And right below where he shows us how to check spacing
with dental floss and adjust it with 2x4s. Tsk!

I found a 2003 post from Mike Yankee to this group:
http://groups.google.ca/group/rec.b...&lnk=gst&q=dropout+alignment#30244bd93d7c2796
But he inexplicably uses separate tools to check and adjust alignment,
awkward. I think my solution was better so I'm posting about it.

I didn't have any spare axles today, so I went to the hardware store
and picked up a pair of threaded rods, about a foot long, and a
handfull of bolts and washers. Total cost around $3. The rod slides
into the dropout, all the way, and is fixed in place by a pair of nuts
and some large washers (hand pressure only). Most of the rod extends
away from the center of the bike, with about an inch going towards the
other dropout. Onto the inner part of the rod I threaded a tall (about
5cm long) nut. Repeat for the other side.

The tool now functions identically to the park tool. Turn the tall
nuts until they are nearly touching, and provide visual indication of
alignment. Gently bend each side as necessary, using the rod for
leverage. It took me longer to thread the nuts and washers onto the
rods in the right order than it did to fix the dropouts, and the wheel
goes in no problemo now.

Of course the same precautions apply as with the park tool - don't
bend aluminum or carbon fiber frames, or frames with beefy forged
dropouts, be careful with frames that are badly bent and inspect for
cracks after. My tool might not have as fine a tolerance as the park
tool, but who cares? If I had had access to my usual junkpile of old
parts I could have made one in a few minutes for no money, although
maybe dropping a couple of dollars for longer rods made it easier.
Considering how easy this was to do, I'm not sure why home mechanics
are so reluctant to try. If my bike falls apart in traffic tomorrow
I'll retract that.

If anyone is interested, and didn't quite grasp the brilliant
simplicity of the procedure from my description, I can take some
photos. I've been away from RBT for some time, but I'm glad to be
back. I'd forgotten how much I love datakolls posts and Jobst-vs-
everyone arguments!

clumsymechanic

 

[datakoll]

right. forget using string from headtube back each side? secure to the
rear then measure?

A threaded rod assembly is useable pressing cups into a steel headtube
painted and/or lubed with linseed oil.

 

[still just me]

On Thu, 28 Feb 2008 21:18:01 -0800 (PST), [email protected] wrote:

>The tool now functions identically to the park tool. Turn the tall
>nuts until they are nearly touching, and provide visual indication of
>alignment. Gently bend each side as necessary, using the rod for
>leverage. It took me longer to thread the nuts and washers onto the
>rods in the right order than it did to fix the dropouts, and the wheel
>goes in no problemo now.

Nice technique. One issue I see is that the nuts are still relatively
short and do not give a long plane to watch. You could fix that by
using large washers between two nuts at the end of the rods for the
visual alignment... or even physical measurement of top and bottom
gaps.

The other issue I see is that you could actually be creating a
parallelogram if you don't have some indication of vertical as defined
by the seat tube... or if the dropouts are not aligned equally in the
horizontal plane.

 

[Joel Mayes]

On 2008-02-29, still just me <[email protected]> wrote:
> On Thu, 28 Feb 2008 21:18:01 -0800 (PST), [email protected] wrote:
>
>>The tool now functions identically to the park tool. Turn the tall
>>nuts until they are nearly touching, and provide visual indication of
>>alignment. Gently bend each side as necessary, using the rod for
>>leverage. It took me longer to thread the nuts and washers onto the
>>rods in the right order than it did to fix the dropouts, and the wheel
>>goes in no problemo now.
>
> Nice technique. One issue I see is that the nuts are still relatively
> short and do not give a long plane to watch. You could fix that by
> using large washers between two nuts at the end of the rods for the
> visual alignment... or even physical measurement of top and bottom
> gaps.
>
> The other issue I see is that you could actually be creating a
> parallelogram if you don't have some indication of vertical as defined
> by the seat tube... or if the dropouts are not aligned equally in the
> horizontal plane.

A third issue is that all-thread rods, particularly in smaller sizes
like used here are commonly more than a little bent, and will become
more bent with this sort of use.

Probably more than good enough for a home job though.

Cheers

Joel
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