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Extra Revolutions on Rough Ground
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Picture of Pete Riegel
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Extra Revolutions on Rough Ground

I use two electronic counters, and always check one against the other. One counter has four magnets and one uses only one.

I had to cross a short construction area (30 m or so) on a recent measurement. The ground was very bumpy. While pushing the bike I came up against a large clod, and the bike stopped momentarily. I saw that the single magnet moved backward a bit, past the sensor. When I got to the other side of the construction I saw that the single-magnet counter had recorded one more revolution than the four-magnet counter.

Form now on I will stop and establish a reference point on each side of rough ground, and observe carefully.

If I had only the single-magnet counter I would have recorded an extra two meters in my layout, and no easy way to check.

I noticed a similar effect when measuring up a long flight of stairs. The wheel jerked around when bumping my way up and down the stairs, and I collected several extra revolutions.

Super vigilance is needed under non-smooth conditions.

This message has been edited. Last edited by: Pete Riegel,


Pete Riegel
 
Posts: 1747 | Location: Columbus, Ohio, USA | Registered: 23 October 2004Reply With QuoteReport This Post
Picture of Neville
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As compared to the Jones counter, extra attention is needed with the Protege when making measurements while walking the bicycle up high curbs, stairs, and deep ruts. I encountered just such conditions while certifying a trail around the campus of Duke University, because it cut across many entrance roads with very high curbs. To ensure that he is not registering spurious impulses,the measurer needs to keep his eye on the meter each time the rim passes through zero to check that it is only incrementing by one.
 
Posts: 304 | Registered: 01 November 2004Reply With QuoteReport This Post
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