Motorcycle-Glossary.com » H

Hairpin

admin — Sat, 06 Sep 2008 20:00:52 +0000

A very slow, tight, sometimes 180-degree, turn.

Hard Tail

admin — Fri, 05 Sep 2008 20:00:54 +0000

Refers to a bike with no rear suspension. Harley-Davidson motorcycles were all Hard Tails until 1958 when the Duo-Glide was introduced.

Head Tube

admin — Thu, 04 Sep 2008 20:00:04 +0000

The outer tube which holds the bearings that allow the front fork steer tube to pivot freely.

Helical Gear

admin — Wed, 03 Sep 2008 20:00:26 +0000

The leading edges of the teeth are not parallel to the axis of rotation, but are set at an angle. Since the gear is curved, this angling causes the tooth shape to be a segment of a helix. The angled teeth engage more gradually than do spur gear teeth. This causes helical gears to run more smoothly and quietly than straight-cut gears. Helical gears also offer the possibility of using non-parallel shafts.

High Side

admin — Tue, 02 Sep 2008 20:00:25 +0000

A type of motorcycle crash that occurs when the rear wheel starts to slide in a turn (sometimes due to a locked brake and the resulting skidding tire), and then suddenly grips the pavement (which could occur when letting off the brake) flipping the bike sideways. The name derives from the side of the motorcycle that the rider will separate from. If forcibly thrown over the bike, the rider is said to have dismounted on the high side.

Riders are usually advised to do a lowsider rather than a highsider if neither can be avoided. The highsider has the additional disadvantage of the rider often being catapulted into the air by the sudden jerking motion of the motorbike and the increased possibility of the motorbike sliding behind the rider with the potential of striking him or her.

Because highside accidents are so much more deadly than lowside accidents, the Motorcycle Safety Foundation recommends that if a rider locks the rear brake, it should be kept locked until the motorcycle comes to a stop. If necessary, locking the front brake to deliberately cause a lowside is recommended. (Compare Low Side).

Holeshot

admin — Mon, 01 Sep 2008 20:00:00 +0000

In motorcycle racing, the drive from a standing start up to racing speed. Generally, the rider who makes the strongest start is said to have gotten the “holeshot.”

Homologation

admin — Sat, 30 Aug 2008 20:00:24 +0000

Homologate means “to approve, especially to confirm officially.” Homologation is the approval process of the governing body over a competitive race. The process certifies that each of the competiting motorcycles (or automobiles) have met all the prescribed racing standards.

In racing series that are “production-based,” (that is, the vehicles entered in the series are based on production vehicles for sale to the public), homologation entails not only compliance with a racing series technical guidelines (for example, engine displacement, chassis construction, suspension design and such) but it often includes minimum levels of sales to ensure that vehicles are not designed and produced solely for racing in that series. Since such vehicles are primarily intended for the race track, use on public roadways is generally a secondary design consideration, except as required to meet government regulations.

Horizontally Opposed

admin — Fri, 29 Aug 2008 20:00:38 +0000

Type of engine layout in which the cylinders are placed at 180° to one another. It is also described as a flat twin or flat four, etc. Also known as a boxer engine.

Horsepower

admin — Thu, 28 Aug 2008 20:00:21 +0000

A unit of measurement used to describe an engine’s strength. Typically, the more horsepower an engine produces, the faster the motorcycle can potentially go. The term “horsepower” was invented by James Watt in 1782 to help market his steam engine and refers to the power exerted by a horse in pulling. (See also: Brake Horsepower).

Hub-Center Steering

admin — Wed, 27 Aug 2008 20:00:20 +0000

One of several different types of front-end suspension/steering mechanisms used in motorcycles. Hub-center steering is characterized by a swingarm that extends from the bottom of the engine/frame to the center of the front wheel instead of two forks.

The advantages of using a hub-center steering system instead of a more conventional motorcycle fork are that hub-center steer separates the steering, braking, and suspension functions. With a fork the braking forces are put through the suspension, a situation that leads to the suspension being compressed, using up a large amount of suspension travel which makes dealing with bumps and other road irregularities extremely difficult. Also, having the steering working through the forks also causes problems with stiction, decreasing the effectiveness of the suspension.

Its complicated assembly is only one of the reasons hub-center steering is implemented in relatively few motorcycle models. The telescopic fork steering system is much more commonly used.