Trail

A trail is usually a path, track or unpaved lane or road, though the term is also applied, in North America, to routes along rivers, and sometimes to highways. In the United Kingdom and the Republic of Ireland path or footpath is the preferred term for a walking trail. Some trails are single use and can only be used for walking, cycling, horse riding, snow shoeing, cross-country skiing, etc., others, as in the case of a bridleway in the UK, are multi-use, and can be used by walkers, cyclists and equestrians.

There are also unpaved trails used by dirt bikes and other off road vehicles. In some places, like the Alps, trails are used for moving cattle and other livestock (see transhumance). In the US historically, the term was used for a route into or through wild territory used by emigrants (e.g. the Oregon Trail).

Usage

In Australia, the term track can be used interchangeably with trail, and can refer to anything from a dirt road to an unpaved pedestrian path. The term trail gained popularity during World War II, when many servicemen from the United States were stationed in Australia, which probably influenced its being adopted by elements of the Australian media at the time (see Kokoda Track).

Glossary of graph theory

This is a glossary of graph theory. Graph theory is the study of graphs, systems of nodes or vertices connected in pairs by edges.

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A

B

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D

E

F

G

H

I

K

κ(G) is the size of the maximum clique in G; see clique.

L

M

N

O

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Q

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T

U

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W

References

Bicycle and motorcycle geometry

Bicycle and motorcycle geometry is the collection of key measurements (lengths and angles) that define a particular bike configuration. Primary among these are wheelbase, steering axis angle, fork offset, and trail. These parameters have a major influence on how a bike handles.

Wheelbase

Wheelbase is the horizontal distance between the centers (or the ground contact points) of the front and rear wheels. Wheelbase is a function of rear frame length, steering axis angle, and fork offset. It is similar to the term wheelbase used for automobiles and trains.

Wheelbase has a major influence on the longitudinal stability of a bike, along with the height of the center of mass of the combined bike and rider. Short bikes are much more suitable for performing wheelies and stoppies.

Steering axis angle

The steering axis angle, also called caster angle, is the angle that the steering axis makes with the horizontal or vertical, depending on convention. The steering axis is the axis about which the steering mechanism (fork, handlebars, front wheel, etc.) pivots. The steering axis angle usually matches the angle of the head tube.