Originally Posted by
pdedes
25 pedal strokes
Honestly this isn't a bad answer.
If I get a chance to preride a course one of the things I'll do is to pick certain points on the course (including the finish), decide what gear I would be attacking/sprinting in and ride the course backwards in that gear until I got to about 25. Then I would pick a landmark like a tree, poll, mailbox etc. and note that as the place to go.
It's most useful in crits.