XI. Perceived disadvantages

1. Undetected spurious impulses will be generated when the wheel rolls backwards.

    If the bicycle is ridden continuously between splits and the counter is rezeroed before the start of each split, there is no chance whatsoever of a problem with spurious counts. I recommend this mode for normal measurement.

    However, if multiple stops for measurements are made without rezeroing the counter, care and checks should be taken to avoid problems. Problems are detected by checking the synchronization of the wheel zero graduation with the zero of the counter.

    If  there is an undue concern with spurious impulses, the single-magnet variation can be used in which these can only be generated by rolling back through the zero graduation on the rim. Stops are normally made only immediately following an increment on the counter and no matter how quick the measurer's reaction time, they are always remote from the zero point on the rim. Altogether, it is extremely difficult to imagine a scenario in which spurious impulses are generated.

2. The sensor will inconsistently detect impulses from the magnets.

    I have found with  three sensors that I have tested that impulses from the magnets are always detected up to a magnet-sensor clearance of  from 8 to 20  mm (center to center) depending on the model. Beyond that limit of full operation, I have not detected any impulses, and if there is a region where there is inconsistent detection, it must be only a fraction of a mm wide. Undetected impulses would reveal themselves by a breakdown in the synchronization of the rim zero point with that of the counter.

3.  The counter cannot be driven backwards.

    Sometimes measurers overshoot an intended measurement point and correct for this by wheeling the bicycle and the Jones backwards even though this is specifically warned against by RRTC Measurement Procedures. Of course electronic counters cannot be run backwards, but a similarly executed correction is available by monitoring how many times the wheel has to go backwards though the zero point. Other corrective procedures are almost the same with both the Jones and electronic counters. (See VI-3.)

4.  The electronic counter method is too complex for anyone but the most competent measurers.

    Actually by requiring fewer readings and calculations the method is actually simpler than that with the Jones. Anyone competent enough to successfully certify a course with the Jones should be able to do the same with an electronic counter.

5.  Total distance is not monitored.

    Actually all cyclocomputers have an odometer mode showing total distance and the Protégés even show this simultaneously with trip distance. The odometer mode has only 10% of the sensitivity of trip distance mode, but this should suffice for the purposes stated for its use: checks of quality assurance by certifiers and reminders of course points.

6.   The meter reading does not always correlate with the rim reading when stopping within 0.01 rev of the rim zero point.

    The accuracy of the correlation of the meter reading with that of the rim when stopping within 0.01 rev of the rim zero point depends on the precision with which the two zero points are aligned. However this is not a problem and precision alignment is not necessary if normal operating procedure is followed and the meter reading is taken before entering this tiny region. Should this be neglected, correct correlation can still be found by moving slightly ahead of the region. In the latter case synchronization should be checked by again moving through the zero point.