Georg Fischer of Switzerland and Davis Components of England made
such similar track fork crowns that for many years I thought they were one crown,
on such diverse bikes as a 1961 Masi and a 1970s Raleigh Pro.
With the help of several people, notably Ken Denny, I'm trying to see the subtle
differences that let us tell one from the other after the fork is brazed and painted.
OK, here's the pic of the Davis crown before I mark it up, thanks Ben for the photo.
Now let's look at my amateurish markups, in the photo below.
See those red lines at an angle to each other?
They indicate the "plate" gets thicker as you move back, toward the bottom of the void.
(OK, we know this is not really a "plate crown" but let's pretend those are plates.)
The blue dimensional lines are my attempt to indicate this thickening.
On the Fischer, I didn't draw the corresponding red lines, but they would be parallel.
The Fischer "plates" are not thicker in the center, they are constant thickness.
The other big difference between Fischer and Davis is the height of the "pedestal",
that holds the crown race of the headset bearing up above the upper plate.
The Fischer has a tall pedestal with a noticeable fillet, the curved transition
from the flat top of the plate to the cylindrical shape of the pedestal.
The Davis has almost no pedestal, and almost no fillet either, putting
the headset almost right down on the top of the top plate.
Now look at the two crowns in the photo below. I think they're both Fischers.
The upper one has a low pedestal, but I think that's because Masi machined it down.
So we see, a low pedestal alone isn't enough proof that a crown is a Davis.
If you machine down the pedestal on a Fischer, you still have the big curved
fillet on top of the top plate. This fillet causes the front edge of the plate
to bulge upward in the center. I've called out this bulge with red, below:
Notice how the front edge of the top plate on the Davis has no such bulge -
The red lines are parallel. (Well, pretend I can draw a straight line...)
There are more differences, but that's enough for now...
Please email TrackCrowns@bulgier.net with any corrections, additions, questions.