There is a standard shorthand method for writing down the rhythm for a series of chords or notes without referring to their pitch. It is most often used with chord progressions and forms a compromise between a simple “chord chart” which conveys only limited information about rhythm, and full musical notation, which conveys all the information you need but takes much longer to write out.
Rhythm charts do vary somewhat – as do all shorthand styles – and you may come across slightly different symbols, but the basic principle remains the same.
All rhythm charts use bars and time signatures in the standard way. Chord names are written in above or below the staff. The precise rhythm in which they are played is indicated by just the ‘stems” and “flags” of the ordinary note symbols.
The only two notes that cannot be represented by rhythmic shorthand are the whole note and the half note, since the note symbol itself is needed to indicate time value. The way around this is to use vertical strokes representing quarter notes and “tie” together as many of them as necessary.
Counting out rhythms: Complex rhythm patterns can be very difficult to count, especially if they contain short notes and rests. To help you analyze them it is useful to slow the pattern down by dividing the beats in a bar so that the shortest beat has a value of one count. In the bar below we take 4/4 time and make it 8/8 since the eighth note has the shortest duration in that measure. In 4/4 you have 4 beats to the bar with the quarter note getting one beat. In 8/8 you have 8 beats to the measure with the eighth note getting one beat.
This is what it would look like in a rhythm chart.