When the bolero (a slow Latin dance rhythm) is played on the timbales, typically you would play the shells of the instrument – a technique known as the cascara. A common pattern is alternating eighth-notes riding on the outside of each of the shells with a triplet thrown in between the beats 1 and 2 with a tick-tickity-tick groove.
When the bolero elevates in tempo you start encroaching on a cha-cha-cha, where quarter-notes ride on a small cowbell mounted on the timbales. It’s common to blend the cowbell rhythm while still maintaining the cascara rhythm with just one hand.
Start by riding straight eighth-notes on the cascara with your left hand and quarters on the mouth of the small cha-cha cowbell with your right (Fig. 1). Once comfortable with that, play 1 & 2 on the cowbell, but ghost the & towards the back of the bell (Fig. 2).
The & on the bell is the first of the triplet, which you will complete with a double stroke on the cascara with the left hand. The downbeat of 2 can be a rest with the left hand, since you strike the cowbell as the quarter-notes continue through the rest of the bar: R-L-L-R (Fig. 3).