The single stroke roll is just R L R L R L R L — alternating, evenly spaced. There's nothing easier to describe and almost nothing harder to play perfectly even. Two key ideas: every stroke at the same volume, and your hands at exactly the same height.
Build speed by adding density (more notes per beat), not by rushing the hands. Quarter → eighth → sixteenth, each at the same tempo. Your hands learn the motion at the slow density, then carry it into the fast one.
Exercises
1 — Quarter-Note Singles
Sticking: R L R L. One stroke per beat. Watch your stick heights — both sticks should rebound to the same place. If one is higher than the other, even out before adding speed.
2 — Eighth-Note Singles
Sticking: R L R L R L R L. Same tempo as exercise 1, twice the strokes per beat. The tempo doesn't change; only the density does.
3 — Sixteenth-Note Singles (The Roll)
Sticking: R L R L · R L R L · R L R L · R L R L. This is the actual single stroke roll. Even though your hands are moving fast, the metronome pulse is unchanged — beat 1 still lands on the same R it did in exercise 1.
4 — Sixteenths with Accents on the Beat
Same notes as exercise 3, but play the first sixteenth of each beat louder — the > marks show where. Accents land on the R's at counts 1, 2, 3, 4; quiet on every other note. This is how you make the pulse audible inside a stream of even sixteenths.