The kick pedal is a mechanism to play the bass drum with your foot. The movement of the foot is transferred by means of a more or less complex device into a controlled movement of the beater. The beater then hits the drum head - BOOOM. The spring then returns the beater into its starting position. The force developed by the foot when playing should not be underestimated and presents a real challenge to material and construction.
Every kick pedal should be assessed regarding ease of play, silence of mechanism and stability. There are simple kick pedals with little adjustment options and complicated ones with lots of them. The more options, the better. It is easier to adjust to the personal preferences.
One pedal ,one beater the most basic pedal. Single pedals can of course be quite sophisticated in their construction. Basic only applies to having just the one pedal.
The single kick pedal is the classic. All other designs could actually be classified as effect pedals. The single pedal finds its use mostly in Jazz, Country and the less demanding genres of rock. Complete drum sets often come equipped with a single pedal.
Two pedals, two beaters. Not so long ago , the double kick pedal was considered an extra. Nowadays it is almost the basic outfit for drummers in many musical styles. Double pedals allow for a substantially more complex and faster play than single machines. The double pedal also has the advantage that you dont need a second bass drum. This is not only cheaper but enables the drummer to place the pedals much more conveniently. Because only one bass drum is used it is also easier to synchronize the sound compared to two kick drums.
There is a left and a right version for double pedals. The extra pedal is therefore either left or right of the main pedal. Right handed drummers have the extra pedal left and lefties have it right (not to be confused with politics). The extra pedal however is always on the side of the hi hat.
Both pedal units are connected by a cardan drive. Both beaters are located on the right pedal (On right versions only of course). The right beater is played just as in a single pedal by the right foot. The second beater is operated by the extra pedal on the left via the cardan drive. This drive has two joints and is telescopic which makes positioning easy. The left pedal however can easily slip. It is imperative when setting up the drums to ensure stable positioning of the auxiliary pedal. Spurs alone are not sufficient. It is best to connect the unit with the hi hat using a multi clamp (accessories) or a base plate.
The FX pedal is a single pedal with two beaters. The actual foot pedal is split into a heel and a ball section. One beater is operated by the heel, the other by the ball. Extremely complex and fast patterns can be performed with this device. If you are used to play a standard pedal though, you are in for a steep learning curve.
The triple pedal is a combination of FX - and a double pedal. The main side has the ball/heal split and the other a regular single pedal. It operates two beaters one is double engaged by the auxiliary pedal. The triple pedal is currently the most complex on the market and has huge musical potential. Just like the FX it needs getting used to. (Thomas Lang released an excellent DVD covering FX pedals ;-) )