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Sheldon Brown's Bicycle Glossary An-Az

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Anatomic
Marketing term to describe a bicycle part that is purported to be better fitted to the cyclists' anatomy than other designs. The term has specific customary meanings in the bicycle industry:
  • Anatomic saddles are those with two bumps and a valley between at the rear. This design is usually associated with Avocet, but has been widely copied since.
  • Anatomic brake lever hoods are specifically shaped to fit left and right hands. This design was popularized by Modolo.
  • Anatomic handlebars are drop bars that have straight sections to fit the hands, particularly just below the brake levers. This design is covered by a Modolo patent.
Anchor bolt
A bolt that clamps down on the plain end of a cable to hold it in place. Many anchor bolts have a hole drilled crosswise through them for the cable to go through, then a nut and washer clamp down on the cable. Other anchor bolts use special washers to clamp cables that run just to the side of the anchor bolt.
Angles
The usual angles that are referred to in frame design are the head-tube (or fork) angle and the seat-tube angle. These angles are usually measured with reference to the horizontal. The typical range is from 68 to 75 degrees.

In general, bicycles with shallower, "slack", "relaxed" angles (lower numbers) tend to be more stable and comfortable. Bicycles with steeper, more upright angles (higher numbers) tend to be manuverable, but less comfortable on rough surfaces. Shallower frames tend to have longer wheel bases than more upright frames; bicycles with shallower head angles normally have more fork rake. All of these factors contribute to the riding characteristics cited.

Ankling
Some older cycling books and articles recommend the practice of "ankling." This refers to changing the angle of the foot fairly drastically during the course of the pedal stroke, so that the toe is pointed upward at the top of the stroke, and downward at the bottom. The idea is to make more use of the muscles of the lower leg, and to permit "pedaling in circles", i.e., applying more force to the cranks at top and bottom dead center.

This practice is pretty much discredited these days. If carried to an extreme, it can cause injury. This happened to me when I was a teenager; I had read about ankling, and had just acquired my first pair of toe clips, just before setting out on my first overnight tour. I ankled for about the first 30-40 miles, when there was a sudden sharp pain in one of my Achilles tendons. I had to lower the saddle, remove the toe clips, and finish out the 4 day tour pedaling on my arches, because I couldn't bear the slightest load on the front of my foot, pulling on the Achilles tendons. For about a month thereafter, I would need to massage my Achilles tendons for about 5 minutes each morning before I would be able to walk. 40 years later, I've still not completely recovered from this injury.

Jobst Brandt on Ankling

Anodized, anodizing
Anodizing is an electroplating process commonly performed on aluminum parts, which forms a thin. protective film of oxidized metal on the surface. Anodizing is sometimes accompanied by the use of a colored dye, which gives a lustrous colored finish to the aluminum parts.

Some rims are "hard" anodized, which produces a hard surface, harder than the natural aluminum, usually in a dark brown or black. This process was popular in the 1980s, as it was presumed to improve the durability of the rim's braking surface, and to make the rim more resistant to cracking around the spoke holes.

Unfortunately, the anodized braking surfaces did not provide as good a grip as natural aluminum, and they presented an unsightly appearance as the dark coating wore off of the sides of the rim.

Even more unfortunately, it developed that the harder surface was also more brittle, causing more problems with cracking around the spoke holes.

Anti-rotation WasherAnti-Rotation Washer
Internal gear hubs use the axle as a fulcrum for the gearing, tending to twist the axle, and in opposite directions in some gears. Such hubs need some method of keeping the axle from rotating in the frame. The most common approach is to use special washers with tabs that fit into the dropout's slot and keep the axle from turning.

The 14 speed Rohloff Speedhub has such a wide gear range that simple anti-rotation washers aren't sufficient, so it uses either a special dropout or a reaction arm connecting to a disc brake braze-on.

Aquaplaning
Alternate (chiefly British?) term for "hydroplaning."

Strictly speaking, this is probably a more linguistically pure term, as both parts of the word have Latin roots. "Hydroplaning" is mixed Greek/Latin, which is not favored by linguists.

Arch (brake)
An incorrect term for the caliper or set of cantilevers that press against the wheel rim. This term first appeared in Shimano literature. I believe that it is a result of poor translation from the Japanese. Since an "arch" is a rigid structure, it is a poor choice to describe a moving part.

The term "brake arch" does legitimately apply to the part of a suspension fork that links the sliders and contains the cable housing stop.

ASS
Above-Seat Steering
ATB
"All Terrain Bicycle." A passé term for mountain bike.
Ashtabula ® crank
A one-piece crank. Ashtabula is a city in Ohio where such cranks were formerly made, by a company of the same name.

See my article on One-piece Cranks.

Audax
Audax is a highly-structured style of club riding popular in parts of Europe. Audax clubs ride in precise formation, usually a double pace line, at a fixed average speed -- 20, 22.5 or 25 km/h,, with a set schedule of rest stops "by the clock." Riders do not take turns "pulling" as with normal pace lines, but a pair of designated, very strong riders is permanently stationed at the front of the peloton.

Similar Audax events also exist for hiking, swimming, rowing and cross-country skiing. Audax is a registered trademark of the Union des Audax Français.

Autobike ®
A crudely built bike, with a rudimentary automatic transmission. This is marketed for people who think they are too stupid to be able to learn to operate a normal bicycle.

It uses a standard derailer operated by a system of weights and springs in the rear wheel.

As the speed increases, the weights move outward due to "centrifugal force", pushing a ring that rubs on the derailer outward, causing the derailer to shift to a higher gear.

There is no provision for the rider to have any control over the gear shifting.

Autoshifting
Refers to a bicycle's shifting gears spontaneously. See my separate article on Autoshifting
Avocet ®
A prominent U.S. maker/importer of bicycle parts and accessories.

Avocet is best known for cyclecomputers, tires and saddles.

The Avocet 20 cyclecomputer was the first to sell for less than $40. Unfortunately, it was widely advertised, with a price of $24.95, for almost two years before it was actually ready to ship. This "vaporware" did great harm to the development of the cyclecomputer market for a couple of years. Avocet cyclcomputers work on an entirely different principle from all other makes.

Avocet was the first to market tires with perfectly smooth tread for road use. They are extremely good, but it is hard to convince people that they get good traction (they do!)

Avocet's first claim to fame was its saddles, which were the first serious alternative to traditional leather saddles. They were the first to use the "two-bump" design to reduce pressure on the perineum.

Avocet also used to market hubs and cranks made by Ofmega in Italy.

The name "Avocet" is pronounced "A-vo-cette". Despite appearances, it is an English word, not French, and refers to a particular shorebird species.

Axle
The shaft at the middle of a bearing. There is some controversy as to whether "axle" or "spindle" should be used in particular contexts. The distinction is based on whether the axle/spindle is stationary, as that in a hub, or rotates, as that in a bottom bracket. There have been bitter flame wars fought in magazine letters columns over this point.
Axle set
A hub axle, plus the cones, nuts, and washers that attach to it.

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