5. THE JONES COUNTER (Go to Lessons Menu)
How do we measure the revolutions of the front wheel?
When in 1961 John Jewell of the RRC developed the calibrated bicycle method for measuring road races he used a revolution counter to count the whole rotations of the front wheel of his bicycle and counted the number of spokes for fractions of a revolution. In 1970 Alan Jones designed a geared counter which would count fractions of a revolution. Today we use a version of this, the Jones-Riegel Counter.
 |
The Jones-Riegel Counter mounts between the left front fork and the wheel. The picture shows the view looking over the front handle bars and down on the counter. The reading shown is between 11,578 and 11,579. We would record this as 11578.5 when calibrating the bike a a short calibration course. When measuring a 10k we would record to the nearest whole number of counts. in this case either 11,578 or 11,579. When the counter reaches 99,999 it "rolls over" to 00,000, so in the calculations we have to remember to add 100,000 every time it has rolled over. We will include examples of this in the exercises which follow. You have to be alert to spot when this has happened. When you are bicycling along you will not be watching the counter closely enough to notice it actually happening.
Image updated 24 April 2010.
|