PROTEGE CYLCOCOMPUTERS AS REVOLUTION COUNTERS IN THE RRTC METHOD FOR COURSE MEASUREMENT
NEVILLE F WOOD
5309 CHAMISAL PL, RALEIGH NC 27613
Revised 8 March 06
ABSTRACT
I describe the operation of Protege electronic cyclocomputers that allows them to be used as precise revolution counters for bicycle wheels in the RRTC method for the measurement of running courses. A slightly simplified description of the operation is as follows. A wheel circumference of 10 meters is set into computer memory, so that for every revolution it senses that the wheel has traveled 10 meters and it therefore increments the displayed trip distance correspondingly by 10 meters or one digit. Thus the trip distance display can be taken as showing the number of whole revolutions, and precise synchronization with a graduated wheel rim allows measurement to within 0.01 rev.
Protege counters offer many advantages over the Jones, a non-zeroing mechanical counter, recommended in the current RRTC method:
1. Clarity of readings -- The standard Jones is mounted on the wheel axel with the display at right angles to the normal direction of eye scan. In contrast, the Protege is mounted on the handlebars and has a display that is 50% larger, so that it can be read comfortably while riding. Road safety, the ability to do night measurements, and error rate are all improved.
2. Instant zeroing capability -- Far fewer readings and calculations are necessary, so that efficiency is improved and error rate reduced.
3. Permanent installation -- Many measurers will want to remove the Jones after use because of noise, drag, and wear. The Proteges can stay in place and be instantly converted to normal bicycle computers.
4. Availability -- The Jones is available from only one supplier whereas the Proteges are available at many bicycle stores and on-line sites.
5. Cheapness -- The Jones costs $80-120 whereas a Protege can be had for as little as $15.
6. No wrap-around -- With the Protege counters the meter display never returns to zero before the end of the measurement, whereas this is always a possibility with the Jones.
7. Display freezing -- By moving the body of the Protege slightly back on its mount, the display can be frozen while the bicycle is wheeled away. This has several applications including the riding of off-set courses. The equivalent procedure with the Jones is to hold the front handbrake on while the bicycle is carried away.
CONTENTS
I. Introduction
III. Computer Programming
V. Installation
VI. Basic Measurement Procedure
VII. Advanced Measurement Procedures
VIII. Methods for Splits
IX. Correction for Overshoot Errors
X. Half-Marathon and Longer Distances
XI. Advantages
XII. Example of Actual Course Certification