Calibrating a bike computer
04-01-19 | 04:44 AM
#1
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What??? Only 2 wheels?
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Calibrating a bike computer
I'm using what they call a computer, really just a speedometer/odometer, that uses a magnet on one of the spokes. (Why do they call it a computer?) I'm thinking of switching in a 32 spoke front wheel in place of the original 36 spoke wheel. Will I have to re-calibrate the computer?
Thanks.
Thanks.
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04-01-19 | 05:06 AM
#2
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You are supposed to put one magnet on every spoke on the side of the sensor, which would be 18 magnets for a 36 spoke wheel and 16 for a 32. Putting only one magnet on your wheel to save weight reduces the accuracy of the speedometer as it will only read once per revolution instead of 16-18 times and is a potential safety hazard, throwing the wheel off balance, ruining handling and potentially causing injury or death.
04-01-19 | 05:13 AM
#3
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Be careful on how you orient the magnet on the spoke.
If you are in the Northern hemisphere, the north pole of the magnet should be facing the drive side. If you live in Australia, north pole should face the non-drive side.
BTW, you will go faster if you place the magnet and sensor as close to the rim as posible
If you are in the Northern hemisphere, the north pole of the magnet should be facing the drive side. If you live in Australia, north pole should face the non-drive side.
BTW, you will go faster if you place the magnet and sensor as close to the rim as posible
04-01-19 | 05:24 AM
#4
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You don't have to perform re-calibration, provided you're using the same diameter wheel. Theoretically, you should preform re-calibration if you change tyre widths, as the circumference will change and the speed/distance are calculated based on the circumference.
Mechanical speedometers and odometers only provide speed and distance By incorporating electronics additional data can be computed such as average speed. Generally, once any electronically performed calculation is involved, it is classified as a computer.
Mechanical speedometers and odometers only provide speed and distance By incorporating electronics additional data can be computed such as average speed. Generally, once any electronically performed calculation is involved, it is classified as a computer.
04-01-19 | 06:21 AM
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04-01-19 | 06:39 AM
#7
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What??? Only 2 wheels?
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04-01-19 | 06:40 AM
#8
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[MENTION=20650]T-Mar[/MENTION]: 
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Tom Reingold, tom@noglider.com
New York City and High Falls, NY
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“When man invented the bicycle he reached the peak of his attainments.” — Elizabeth West, US author
Please email me rather than PM'ing me. Thanks.
04-01-19 | 11:36 AM
#9
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No, not if you carefully measure the distance from the hub to the magnet along the spoke on the old wheel and then on the new wheel put the magnet 12.5% farther away. If it seems you’re going too fast or too slow then it actually should be 12.5% closer to the hub. < — Math ( 36-32 ) / 32 . I can never remember which direction you’re supposed to move it (Don’t get me started on Italian threaded front hubs).
If you already took the magnet off the old wheel, you’re screwed and will have to recalibrate.
If you already took the magnet off the old wheel, you’re screwed and will have to recalibrate.
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04-01-19 | 11:45 AM
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Metric or Standard Magnet?
04-01-19 | 01:22 PM
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04-01-19 | 01:34 PM
#14
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You move the little red plastic wheel that touches the tire up and down a little until the odometer matches up exactly with the county road mile markers. The magnet is completely unnecessary.
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