How far the speedometer magnet?
03-24-09, 08:52 AM
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How far the speedometer magnet?
Hi Everyone
A simple question to which I find myself puzzled... how close does the speedometer magnet need to be from the rim in order to get a true reading?
Thanks in advance
Mike
A simple question to which I find myself puzzled... how close does the speedometer magnet need to be from the rim in order to get a true reading?
Thanks in advance
Mike
03-24-09, 08:56 AM
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The reading will be the same no matter where the magnet is placed along the spokes between the rim and the hub. The magnet goes by the pickup coil/switch once per revolution no matter where it is.
In some cases putting the magnet way out near the rim can give reading problems as the magnet goes by the pickup too fast (linear speed, not rpm) for the pulse to register but, if the pickup gets the signal, it doesn't care where the magnet is.
In some cases putting the magnet way out near the rim can give reading problems as the magnet goes by the pickup too fast (linear speed, not rpm) for the pulse to register but, if the pickup gets the signal, it doesn't care where the magnet is.
03-24-09, 09:24 AM
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I always put the magnet as close to the hub as I can because it travels much slower and gives a pulse when you place it out near the rim its traveling at a much faster speed as it passes the pickup.
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It may not be fancy but it gets me were I need to go.
https://www.jtgraphics.net/cyclist_bicycles.htm
03-24-09, 09:55 AM
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I, like JTGraphics, usually put mine fairly close to the hub. Some magnets seem to stay put best if I install them tucked into the rim side of the V where the third spoke crossing is on a 3X laced wheel. That's about 1/3 of the distance from the hub to the rim.
03-24-09, 11:11 AM
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The Cat-Eye wireless computers have a maximum transmission distance of 70 cm (27.5") between the fork mounted sensor and the cyclometer head so on larger frames, the sensor and magnet may have to be higher on the fork to keep within that distance. Actually having them closer together is better so the magnet may be placed nearer the rim to get the sensor closer to the head. This is not an issue with wired cyclometers.
BTW, I never saw a "12mm optimum distance" from anything mentioned in Cat-Eye's .pdf of their Wireless Strada installation sheet. The only recommended dimensions given are 70cm max between the sensor and cyclometer head and 5mm maximum gap between the sensor face and the wheel magnet.
BTW, I never saw a "12mm optimum distance" from anything mentioned in Cat-Eye's .pdf of their Wireless Strada installation sheet. The only recommended dimensions given are 70cm max between the sensor and cyclometer head and 5mm maximum gap between the sensor face and the wheel magnet.
03-24-09, 11:49 AM
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Between the magnet and the sensor. And he's right - it is 5mm for the Cateye. I was thinking of an older toy. If too close - it won't read. Too far - won't read. It's a narrow window. Fortunately these things stay put once you properly install them.
