In a gear change it is mainly the feel of the music that changes; the tempo itself usually stays the same. A new gear can sound lighter, heavier or denser, which makes the music seem to speed up or slow down.
In timba the tempo usually stays the same. What changes in a gear change is mostly the feel: the percussion and the bass switch patterns together, which makes the music sound lighter, heavier, fuller or barer.
Stay with the pulse: even when the music suddenly sounds "faster", the beat is often still in the same place. Adjust your energy and style, not straight away your tempo.