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Appologies in advance for what is probably a very dumb question.

I am in the process of fitting a cateye Astrale 8 computer to my bike and the install instructions are a bit lacking. Does it matter where on the wheel and crank arm I place the sensors? From what I can see the computer comes up with a set number of wheel sizes to calculate the data. Surely the data collected from the sensor close to the hub will be different to that closer to the rim.
 

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don't believe it matters.

the sensor isn't calculating the distance, just the numbers of revolutions. once around is once around whether it's close to the hub or out toward the rim. i have mine fairly close to the hub just because that's where it all fit best. i imagine the closer to the rim the less protected it would be.
 

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A little

bits said:
Does it matter where on the wheel and crank arm I place the sensors? Surely the data collected from the sensor close to the hub will be different to that closer to the rim.
The answers to your questions are: a little, and no. As you move the sensor closer to the rim, the amount of time it spends near the pickup gets shorter. If you have a sensitivity problem, this can be fixed/helped by moving the sensor closer to the hub. The calculations that the computer goes through are based on the number of "clicks" it sees from the sensor - it has no relation to wheel diameter except for the number you put in the computer to calibrate it. On the same wheel, the computer sees the same number of "clicks per mile" whether the sensor is right at the hub or right at the rim.
 

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I just installed an Astralle 8 this weekend. It doesnt matter where you place the sensors, jsut make sure they are at a spot where you can put the receiver less than 5mm away from the sensor.
 

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wut?
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bits said:
Appologies in advance for what is probably a very dumb question.

I am in the process of fitting a cateye Astrale 8 computer to my bike and the install instructions are a bit lacking. Does it matter where on the wheel and crank arm I place the sensors? From what I can see the computer comes up with a set number of wheel sizes to calculate the data. Surely the data collected from the sensor close to the hub will be different to that closer to the rim.
I thought the same thing when I was installing mine. I kept thinking if I placed it closer it'd pass by the sensor more frequently. This is obviously erroneous thinking. I felt kind of dumb when I realized this. No offense. :)
 

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Collin's Dad
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Don't worry scotty, closer to the hub it does spend more time in front of the sensor. If you want the sensor and magnet to spend lots of time together, than sure move it to towards the hub. NTTAWT HTH
 

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Think about it this way... (using a front wheel mounted sensor)

Think of your fork (straight, no rake) as a plane. Every time the sensor passes this plane, the computer "counts" the passing of the sensor (position is not relevant). Now, instead of thinking of the sensor as a single point on the spoke, think of the entire spoke as a singe sensor. The spoke passes through this plane evenly, meaning the point closest to the hub passes through this plane at the same time as the point on the spoke closest to the rim.

This is more of a mathematical/physics way of looking at the position.
 
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