Let’s talk about rhythm.
First, let’s be clear about the difference between rhythm and tempo.
Tempo is the musical work for speed.
Rhythm is the pattern of long and short notes—the ratio between them.

In our music, we normally find a tempo marking. Sometimes, this is a word like “Allegro” (fast) or “Adagio” (slow). In more modern music, we often have a description that is a little more vague as to the speed—for example, “With Feeling” or “Bluesy.”

In addition to or instead of a description, we have a metronome marking that may, for example, tell us our crochet (or quarter note) should be 60BPM.

Whichever instruction we have, our rhythm will remain EXACTLY at the same ratios. This means that when we practice, we can start slowly and get the rhythm correct, regardless of the tempo.

The Rhythm Tree below shows how this works.
Each of the rows shown adds up to four beats.
A semibreve, for example, should last exactly 4 times the length of a crotchet.
Two quavers should be played in the time one crochet lasts, and so on.

It doesn’t matter if your tempo is fast, slow, or somewhere in between. These rhythm ratios do not change—EVER!