truing a bicycle wheel (useful ascii art)

One of the wheels on my bike had become fairly badly warped.
Investigation revealed a broken spoke. So I called up my friend
Marc, who is much better at bike repair than I am, and talked
to him about it. 

The general theory is that the spokes alternate going to the left
and right side in the center, so when one is loose or broken the
tightly attached spokes from the other side pull the rim in that
direction.

                  _
                /' '\
                |. .|  <- Tire
                 \~/   <- Rim
                  T    <- Spoke nipples
                  |
                 .^,   <- Spokes (two, overlapping at top)
                 | |
                .| |,
                |   |
                [===]  <- Axel

Above, the wheel in cross-section. Below in profile (imagine it to
be rounded instead of straight -- I'm being lazy with the ascii-art).

Key:     !   nipple of broken spoke
         T   nipple of incidental spoke
         7   nipple of spoke to tighten
         Y   nipple of spoke to loosen

  #^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#
                    INFLATE TO 85 PSI
  _____________________________________________________
   T    Y    7    Y    7    !    7    Y    7    Y    T
   |    |    |    |    |    |    |    |    |    |    |
   |    |    |    |    |    |    |    |    |    |    |
       (a)  (b)  (c)  (d)       (d)  (c)  (b)  (a)

  a: loosen a very little
  b: tighten a little
  c: loosen a little
  b: tighten most           (1/2 turn or so)

All fine in theory, in practice it is easy to lose track of
whether clockwise or counterclockwise is tightening, and what
needs to be done to what spoke. Marc told me that he had never
successfully 'trued' a wheel himself. He always made things
worse. 

I managed to keep myself from being confused by using a Sharpie
(permanent felt tip marker) to note on the rim what needed to be
done for each spoke. So after about twenty minutes of planning
and work my wheel is a lot more balanced.

Elijah
------
posted ascii art to the net years ago but found none of it in current archives