(From Eric Anderson, with minor editing by John Hughes)
[Ed note: I mentioned to Eric that at the NEIYA clinic, I'd gotten several opinions from several people about how long the "flat" on a runner should be, and where the flat ought to be centered. I was pleased that there were some differences of opinion, which suggested to me that this was not absolutely critical. I think that the concensus I got on the location of the flat was "centered just about under the runner hole." Then again, I also have the sense that by moving both bits of shimstock forward or aft, you could make the "flat" appear to be located just about anywhere, i.e., this part of the story is a little vague anyhow. Now back to Eric:]
All around good side-runners would be 30" Sarns bull nose. When you sharpen these, you probably want 15" of flat. For the steering runner, a 26" Sarns bull nose, you want about 11-12" flat.
[Ed note: "Flat" here doesn't mean "flat". It means that you rest the runner on its lowest point, and slip some .008 shim stock in from either end until it gets stuck. The "flat" refers to the distance between the two shims. ]
For other kinds of runners:
Racing runners
3/16" X 36" insert runners (side runners) 18" flat
3/16" X 30" insert (steering runner) 12-15" flat
1/4" X36" insert heavy air side runner 24" flat
Slush runners
36" 100° edge 18" flat
Plate runners
26" (snow runners) 12" flat
Plate runners
30" (windy snow runners) 16" flat
All runners except slush runners are ground to a 90° edge. Slush runners are ground to 100°. In reality I did not come up with these numbers, I am just copying what the fast guys do, i.e., Ron Sherry and Matt Struble.
[Ed note: Thanks again to Eric for providing these suggestions.]