science

Suicide clutch

Suicide clutch is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Suicide clutch rather than just read about it. In short: The terms suicide clutch, and suicide shifter or jockey shifter, refer to some motorcycles' foot-operated clutch and hand shifter to change gears. Foot clutches (rocker-clutches) and hand shifters (tank-shifts) were found on early motorcycle designs from around the turn of the 20th century to the 1940s or 50s, and reappearing on modern retro styled custom motorcycles and choppers.

Key takeaways

Suicide clutch belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Suicide clutch to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Suicide clutch from memory before moving on to harder problems.

Reference excerpt

The terms suicide clutch, and suicide shifter or jockey shifter, refer to some motorcycles' foot-operated clutch and hand shifter to change gears. Foot clutches (rocker-clutches) and hand shifters (tank-shifts) were found on early motorcycle designs from around the turn of the 20th century to the 1940s or 50s, and reappearing on modern retro styled custom motorcycles and choppers. Modern motorcycles do not require removing a hand from the handlebars to shift gears, using only the fingers for the clutch and the toes of one foot to select gears. In contrast, the fanciful slang "suicide" was applied to designs where the rider removes one hand to change gears, or cannot put both feet on the ground while using a foot clutch to disengage the transmission. Sometimes the shifter is referred to as a "jockey shifter" while the foot clutch is called a "suicide clutch". Suicide clutches were common on mid-20th century Harley-Davidson motorcycles and many custom bikes today still employ this system. Harley-Davidson introduced the hand clutch on the 1952 Panhead. More technically, "suicide clutch" can refer to clutch controls lacking a detent on the foot clutch, which would otherwise allow the rider to lock the clutch in the disengaged position. Early foot-clutch motorcycles, such as those from Harley-Davidson and Indian, allowed the rider to lock the clutch foot pedal due to its over-center geometry plus a helper spring (aka "sissy spring"), so they could place both feet on the ground when stopped. These standard clutches are called a "rocker clutch". If this device was disabled, or a custom foot clutch was installed that had no detent, it was referred to as a "suicide clutch" because stopping the motorcycle in-gear required the rider to keep his foot on the pedal. Should he lose his balance and put the left foot down, the motorcycle could lurch forward into cross traffic. The suicide clutch, especially on a chopper with no front brake, also made stopping at a red light on a hill especially precarious. The suicide clutch is sometimes incorrectly called a suicide shifter. The suicide clutch is a foot-operated clutch that is mounted on the left side of the motorcycle's forward foot controls. The suicide-clutch moniker has derived from difficulties in operating this form of clutch and shifter. On a motorcycle equipped with a conventional hand clutch and foot shifter, the rider places the left foot on the ground when stopped and holds the motorcycle in place with pressure on the rear brake pedal with the right foot, while engaging the clutch with the left hand. On a motorcycle equipped with a suicide clutch, the clutch is held in with the left foot, requiring the right foot to hold the bike in place, with the right hand applying pressure to the front brake. Early Harley Davidson foot clutches used an over-center spring to hold the clutch pedal in the disengaged position and used a friction disc to allow the rider to adjust the sensitivity of the return. Often riders removed the spring to keep the clutch pedal from returning to the disengaged position while riding. While this spring removal allowed for the clutch to stay engaged better, it also removed the safety feature of the clutch pedal holding itself in the disengaged position. With the pedal not returning to its natural disengaged position, the rider must either shift into neutral or hold the clutch pedal with the left foot when coming to a stop. Early Harley Davidson racers removed the clutch return spring to ensure the clutch stayed in the engaged position throughout the race. This practice soon caught on with other riders. The term "suicide clutch" was coined by those who could not operate the foot clutch proficiently enough to ride a tank shift (or hand shift) motorcycle in normal traffic.

Types of shifters

Regular clutch hand Shifter - This is where the shifter is a regular knob either located on the tank, which operates through a linkage to the transmission (tank shifter) or on a lever bolted directly to the top of the transmission (jockey shifter or slap shifter depending on the transmission design) and involves the semi-complex task of foot clutch operation and hand shifting. The foot is used to operate the clutch pedal clutch lever and the second hand is used to shift gears. Clutched Shifter - This shifter has a clutch lever on it allowing one-handed shifting. This design allows the left foot to be free.

Technical history

… excerpt ends here. Continue reading the full article.

Illustrations

Suicide clutch: Old-style tank shift. — Old-style tank shift.

Worked examples

Example 1 — a first encounter with Suicide clutch

Start with the simplest possible case. Write down what Suicide clutch claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Suicide clutch before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Suicide clutch ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Suicide clutch

In research: Suicide clutch appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Suicide clutch in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Suicide clutch is common in secondary-school and first-year university syllabi. It links to neighbouring topics Clutches, Motorcycle transmissions, so understanding it makes those chapters shorter.
In everyday life: Look for Suicide clutch outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Suicide clutch in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Suicide clutch means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Suicide clutch out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Suicide clutch in simple terms?

Why does Suicide clutch matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Suicide clutch?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Suicide clutch.