computer magnet

[Wheezie]

Hi sorry if this has been covered but when i fit the magnet for my cycle computer should it go as near to the rim as possible? Using the circumference of the wheel as setup data suggests so but its gonna be difficult to do.

 

[Bigtwin]

Errr - no.

The wheel goes that far per revolution. And it does one revolution whether the magnet is at the rim or at the hub flange.

Makes no difference whatsoever.

 

[lazyfatgit]

The magnet switches the sensor every revolution. The computer adds the circumference you have set on every pass. So it doesn't matter where the magnet is.

I think it has the least effect on the rotational moment on the wheel the closer to the hub.

 

[BIGSESAL]

As above.

The cycle computer stores the circumference of the wheel. It multiples the circumference by the roational speed of the wheel (no of rotations in a given time which is independant of where the magnet is placed) to give the distance traveled.

For example if you had a wheel circumference of 1 metre (I just used this size as it was easy) and a roatation speed of 20 rotations per second, the bike would travel 20 meters in that second. This would then be 1200 metres an minute or 1.2km which is 72km/hour. (Ok perhaps a slightly high speed but you can see the kind of calculations that the computer is doing).

 

[Joe24]

As above.

The cycle computer stores the circumference of the wheel. It multiples the circumference by the roational speed of the wheel (no of rotations in a given time which is independant of where the magnet is placed) to give the distance traveled.

For example if you had a wheel circumference of 1 metre (I just used this size as it was easy) and a roatation speed of 20 rotations per second, the bike would travel 20 meters in that second. This would then be 1200 metres an minute or 1.2km which is 72km/hour. (Ok perhaps a slightly high speed but you can see the kind of calculations that the computer is doing).

Woah, hang on Thats some calculations at this time of night

 

[BIGSESAL]

Woah, hang on Thats some calculations at this time of night

Haha, oh how I love physics and maths.

 

[ArtV]

Wireless

If you have a wireless computer, it might be worth moving the magnet/transmitter nearer to the rim just so it's closer to the receiver.

Well, if you have a cheap one

 

[D4VOW]

If you have a wireless computer, it might be worth moving the magnet/transmitter nearer to the rim just so it's closer to the receiver.

Well, if you have a cheap one

+1

If it is wireless put the transmitter near the top of the fork so that the signal stays strong. If it's wired then place it as far down the fork as you can so that you can use up all the unnecessary wire to keep your bike looking clean and tidy

 

[Randochap]

Yep, no dif.

I usually mount mine closer to the hub, as can be seen here.

On all my bikes, I have two computer harnesses -- one is for a multi-function computer, the other includes altimeter. I have doubled up the sensors on one set of zip-ties and run both off one magnet.

Both are wired.

 

[Royalrider]

As BIGSESAL says but in simpler terms. If the spoke you put the magnet on is,say, pointing directly to 12'oclock, when it completes one turn of the wheel the magnet will be back to its starting point no matter where you put it on the length of the spoke.
The sensor only counts turns of the wheel, the computer then does the maths as BIGSESAL eloquently describes depending on the wheel size you told it to work with.
With the Cateye Strada wireless I hve found it doesn't matter where on the fork you put the sensor, the computer picks up the signal, but the lining up of the magnet with the sensor is critical.