[Update:  I'm fixing up this post that rambled off in too many directions - a victim of late night posting.  This post deals with the "Swing Pairs" - similar rhythms that shift between 12/8 and 4/4.  See here for the exercise and chart of the comparison of rumba clavé and 6/8 clavé....]

The  rumba clavé and bembe clavé are what I call a Swing Pair (I use "bembé clavé" and 6/8 clavé interchangeably).  One side of  a swing pair is a 4/4 rhythm that - when played with a certain amount of swing - can shift into the equivalent rhythm in 12/8.  (I'm not talking about playing a 4/4 rhythm then playing a 12/8 pattern within the 4-count.)

For example, a great example of the shift from 4/4 rumba clavé to bembé clavé is on Cachao Lopez' version of the song "La Trompeta y la Flauta" (Last.FM link)

Another great example of this shift is in Radioclit's coupé-decalé mixtape (a recommended download in itself).  The very first song is a straightforward 4/4- you can here the wood-block sounding son (3-2) clavé, and the snare drum is beating out a 4/4 version of.... the first 5 notes of a bembé pattern.  In fact, you may not even realize it until...

...minute 2:10, when the rhythm changes to 12/8, and you hear the full bembé pattern. 

And that switch so beautifully displays the shift from 4/4 to 12/8, I've been wanting to write this post ever since I first heard it.  (So that's almost one year!)

And enjoy the rest of the coupé-decalé mix while you're at it....