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Old 08-06-09, 12:29 PM   #1
G-money
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Unreliable MPH reading on Delphi computer

Last week I got a Delphi bike computer for my Trek 1.5, and installed it myself. The ride mileage and average speed seem fine, but the MPH reading jumps aroud a lot. When I am peddling on the flat under 20 MPH, it seems fine, but If I accellerare or go over 20, the reading jumps back and forth from around 10 to 20 or so. If I stop pedalling and coast, the MPH sometimes steadies out. Worst of all, when I go over 25, the readout sometimes just shows zero!

Any ideas? Maybe I should have spent more than $30, but all I really care about is tracking mileage and knowing reliably how fast I am going.
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Old 08-06-09, 01:36 PM   #2
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Try moving the sensor closer to the magnet and the magnet farther from the hub if possible so the the magnet is passing the sensor "slower". The computer just records front wheel RPM and multiplies that by the diameter of your front tire to compute MPH.
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Old 08-06-09, 04:36 PM   #3
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Moving the magnet further from the hub causes the magnet to pass the sensor faster not slower. And what does that matter anyway?
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Old 08-06-09, 05:47 PM   #4
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you need a better 'puter, that one is junk
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Old 08-06-09, 06:33 PM   #5
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I have a Cateye Enduro 8, does the job for over 4 years.
Under $30 at Amazon.com, free ship

http://www.amazon.com/Cateye-CC-ED30.../dp/B000R5NREY

Rob
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Old 08-07-09, 09:18 AM   #6
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Moving the magnet further from the hub causes the magnet to pass the sensor faster not slower. And what does that matter anyway?
Correct, I was very tired when I wrote that, I was thinking that if the magnet passed the sensor slower, then it might read more reliably, as it has a longer "window" to sense the magnet's passage.
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Old 08-07-09, 09:41 AM   #7
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There's no need to spend over $30. The 17 function `Schwinn' cycle-computer that Amazon sells for $10 works fine at speeds up to 35 mph on my recumbent with 16" tires (so the tire is spinning even faster than a road bike at the same speed would be.) It's also fine on my standard road bike at 40 mph.

(I have no reason to think that 35 mph or 40 mph is a magic figure -- it's just that I don't recall ever getting that particular bike going faster than that. But if it works on the 'bent at 35 mph, it ought to work on a bike with 700c tires at 60 mph.)
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