help needed

Magnet distance from the rim does not matter at all, as long as the magnet can trigger the sensor. The computer measures wheel revolutions per a given time frame, or in other words RPM's. One revolution is one revolution, no matter the magnet placement.

What does matter is making sure the computer is set up for your actual wheel/tire circumference (typically in cm or mm). That way, the computer knows how far you have traveled (circumference) in one revolution, while it also keeps track of the time it took you to travel one revolution.

Assuming you originally set up the computer correctly, and your wheel/tire size is the same as your previous bike, you should not need to change any settings.

Otherwise, go here for a calibration chart and other info:
branfordbike.comcomp10.htmlOpen ↗

hattrick8882 said:

thanks first of all to everyone who responds with an honest answer, i need help, i recently bought a new bike, i had the old bike for about 3 years and i had a wireless cyclometer on the bike, and when i transfered it to the other bike, i couldnt locate the instructions for the computer, so i dont know exactly where to mount the magnet on the spoke, as far as distance from the rim, ive heard that .01 miles should be roughly 7 revolutions, its this a good ratio to go by, or does someone know an exact number as to where the magnet should be, i know i sound silly for this problem, but i just want accurate numbers from the computer, thanks again

It doesn't matter functionally - as Scottydog said, one rev is one rev. There may be an optimum place along your fork to put the sensor so that it doesn't interfere with other parts like the brakes or quick release and doesn't get whacked when you put on your car's roof rack. And there may be an optimum place along your spoke so that the magnet doesn't interfere at a crossing or whatever. And there may be an optimum place where your fork blade and spokes come at the perfect distance apart to put in a magnet and sensor.

Given all that, I'd say about 1/3 the way from your hub to your rim is generally a good spot.

hattrick8882 said:

thanks first of all to everyone who responds with an honest answer, i need help, i recently bought a new bike, i had the old bike for about 3 years and i had a wireless cyclometer on the bike, and when i transfered it to the other bike, i couldnt locate the instructions for the computer, so i dont know exactly where to mount the magnet on the spoke, as far as distance from the rim, ive heard that .01 miles should be roughly 7 revolutions, its this a good ratio to go by, or does someone know an exact number as to where the magnet should be, i know i sound silly for this problem, but i just want accurate numbers from the computer, thanks again

Right, magnet position does not relate at all to the calibration. There is a setting on the computer where you enter your wheel size. You can find wheel size on the side walls of your tire, and you can probably find directions online, depending on what computer you have.

This might be useful, if the model you have is listed...

http://www.sheldonbrown.com/cyclecomputers/index.html

Meanwhile, as I understand it, you want to position the sensor and magnet to optimize for two things: minimum gap between sensor and magnet and minimum distance from hub. The reason for keeping it close to the hub is so that the magnet passes the sensor as slowly as possible, giving the sensor more time to get properly tripped. See Sheldon's 17 tips for this and more...