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The Jones Counter is a device fitted to the front wheel of a bicycle that counts the revolutions of the wheel. It was invented in 1971 by Alan Jones in order to measure the length of
On the right is the original production version, manufactured by Alan Jones's son Clain from 1973 to 1982. The gearing produces 20 counts per revolution of the bicycle wheel.
To measure road-race courses, the counter is fitted to a bicycle between the left fork leg and the front wheel.Picture in course measurement lesson
/ref> The tab or tabs on the large ring gear engage with the spokes, thus providing drive to a Veeder-Root counter. Before the counter is used, the bicycle must first be calibrated by being ridden on a straight section of road between marks whose separation has been accurately measured by steel tape. A calibration can then be calculated in terms of counts per kilometer. Next, the bicycle is ridden over the race course to determine its length. Finally, the bicycle is recalibrated by riding again over the calibration distance. This is done to check for changes in bicycle-wheel diameter due to temperature changes, air leakage, and other causes.
The Measurement of Road Race Courses
' (handbook of the IAAF) Counting instruments Sport of athletics terminology
road running
Road running is the sport of running on a measured course over an established road. This differs from track and field on a regular track and cross country running over natural terrain.
These events are usually classified as long-distance ...
race courses. The counter has gears that drive a mechanical digital counter. One count typically corresponds to about 1/20 of a wheel revolution (this varies if a different gear ratio is used); this provides a resolution of about 10 cm in course length, although overall accuracy, depending on calibration and other factors, is lower, but normally better than 1 part in 1,000.
Almost all road running courses in the world are measured with this device. The Jones Counter has been used to measure all Olympic Marathon courses since the 1976 Montreal Olympics except for the 1980 Moscow Olympics. In addition, it has often been used to measure the Olympic Road Race Courses.
Models
Clain Jones Counter
On the right is the original production version, manufactured by Alan Jones's son Clain from 1973 to 1982. The gearing produces 20 counts per revolution of the bicycle wheel.
NYRRC Jones Counter
Production was taken over byNew York Road Runners
New York Road Runners (NYRR) is a non-profit running organization based in New York City whose mission is to help and inspire people through running. It was founded in 1958 by Ted Corbitt with 47 members and has since grown to a membership of more ...
from 1983 to approximately 1990.
Jones-Oerth Counter
Paul Oerth took up production in approximately 1990 and continued to about 2006. These models have a different gear ratio (260/11 counts per wheel revolution). In 2006, production of the necessary gears ceased, and an alternative plastic-encapsulated set of gears was introduced. This was short-lived, and the Oerth model went out of production.Jones-Oerth-Lacroix Counter
The JOL counter is a variation of the Jones-Oerth model. Created by Laurent Lacroix in 2000, its distinguishing feature is a 27" rotary cable that allows the user to mount the Veeder-Root Counter on the handlebars.Jones Counter model JR
Development of a new model started in 2007. The first production units became available in April 2008 and were used for the measurement of theLondon Marathon
The London Marathon is an annual marathon held in London, United Kingdom, and is the 2nd largest annual road race in the UK, after the Great North Run in Newcastle. Founded by athletes Chris Brasher and John Disley in 1981, it is typically he ...
, which took place on April 13, 2008.
The gearing (260/11 counts per wheel revolution) is identical to that of the Jones-Oerth model.
Use for measuring road-race courses
To measure road-race courses, the counter is fitted to a bicycle between the left fork leg and the front wheel./ref> The tab or tabs on the large ring gear engage with the spokes, thus providing drive to a Veeder-Root counter. Before the counter is used, the bicycle must first be calibrated by being ridden on a straight section of road between marks whose separation has been accurately measured by steel tape. A calibration can then be calculated in terms of counts per kilometer. Next, the bicycle is ridden over the race course to determine its length. Finally, the bicycle is recalibrated by riding again over the calibration distance. This is done to check for changes in bicycle-wheel diameter due to temperature changes, air leakage, and other causes.
See also
* Short course prevention factorReferences
External links
*The Measurement of Road Race Courses
' (handbook of the IAAF) Counting instruments Sport of athletics terminology