Foot clutches with tank shifters were standard on American motorcycles such as Harley-Davidson and Indian up to the mid-20th century and many custom bikes today still employ this system.[
citation needed] The system used by Harley-Davidson arranged the controls with the tank shifter on the left side of the motorcycle, with the throttle operated by the right hand and the shifter, spark control and front brake operated by the left hand. The Harley-Davidson rocker clutch was operated with the left foot with the heel down position to disengage the clutch (with an over-center spring to hold the clutch disengaged) and the toe down position to engage it ("Toe-to-go"). The right foot operated the rear brake, as is the practice in modern times. Indian, meanwhile arranged things differently. On an Indian, the tank shifter was located on the right side of the motorcycle, with the throttle operated by the left hand and the shifter, spark control and front brake operated by the right hand.[
citation needed] (Indian promoted their system to police departments saying that the officer could fire his service weapon with his right hand while riding) The Indian rocker clutch was also operated by the left foot, but the toe down position disengaged the clutch and the heel down position engaged it.[
citation needed] Harley-Davidson introduced the hand clutch on the 1952
Panhead,
[8] and simultaneously on the K model, their all-new sport model.[
citation needed] The transmissions of the foot shift and the hand shift models were different. The hand shift gear selector mechanism was referred to as the "jockey top" or "jockey lid."[
citation needed] On this transmission, the gears were selected in a linear fashion with the selector arm moving further and further forward with each successive gear and the gear lever moved in a slotted gate on the side of the tank. When modified to operate as a "jockey shifter,"[
citation needed] The lever would be pushed back for 1st gear and then step by step more forward for each subsequent gear. The foot shift gear selector mechanism was referred to as the "ratchet top".[
citation needed] On this transmission, the gears were selected in a ratcheting motion, returning to its default, central position after each shift. When modified to operate with short, transmission mounted hand lever and a foot suicide clutch, this type of set-up was referred to as a "slap shifter" or "slapper".[
citation needed] In contrast to the jockey shifter, the slap shifter would always stay in one central position between shifts.[
citation needed] Throughout the 50s and 60s on the Panheads and subsequent Shovelheads, foot clutches and hand clutches coexisted, with the hand clutch being progressively more popular over time.[
citation needed] After foot clutches had all but disappeared from Harley-Davidson civilian models, the last holdout of foot clutches were the police models up to the early 70's, presumably because the police officers could use their 2-way radio with the left hand while clutching with their foot.[
citation needed]
The jockey shifter is a gear shifting device used on motorcycles before the use of a foot-operated shift lever.[
citation needed] A jockey shifter gets its name from the location of the motorcycle rider's hand when shifting gears. It is under his seat like the position of a jockey's hand while using his riding crop on his horse. This hand shifter lever is directly mounted to the transmission and is just long enough to clear the primary drive cover or belt drive.[
citation needed] A motorcycle equipped with this type of shifter requires the use of a foot clutch.[
citation needed] The foot clutch comes in one of two configurations; either a
rocker foot clutch, which was stock on many early motorcycles, or a suicide foot clutch, which was never available on production motorcycles but was manufactured by daring motorcycle enthusiasts. The suicide foot clutch was usually a very simple lever, more or less a mirror image of the rear brake lever on the other side of the motorcycle; like a standard shift car's clutch lever.[
citation needed] The rocker foot clutch is easier to use than the suicide foot clutch because it can be rocked into a position where the clutch is either engaged or disengaged - leaving the rider's foot free to be put down, at a stop, to steady the motorcycle. Sometimes a tank shifter is referred to as a jockey shifter, but this is incorrect due to the rider's hand position being in front of him, not behind him like for a horse jockey. A tank shifter is also connected to the transmission with linkage, which jockey shifters do not use. The earliest known use of a foot clutch and hand shifter, on motorcycles, was with the first multi-geared transmission on the 1915 Harley Davidson.
[10] It is a mechanical linkage that is typically mounted to the left side of the motorbike's fuel tank and is held in place by a slotted piece of metal welded to the frame or the tank.
[9] Through a series of linkages, it is connected to the transmission shift selection lever. In terms comparable to a motorcycle of current construction, it is simply a way to relocate the shift lever from the front foot controls to the side of the gas tank. Early motorcycle customizers who were trying to reduce their motorcycle's weight so as to increase its power-to-weight ratio would sometimes replace their stock rocker foot clutch with a hand fabricated suicide foot clutch, and remove the tank shifter's linkage and instead attach a shifter arm directly to the transmission (jockey shifter). This reduced weight not only made the bike accelerate better, but also gave the rider bragging rights of riding a motorcycle which required more skill to operate.[
citation needed]
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