How does this bike computer fit

russbelluk

Hi guys, first poster here

Just got back into the game, used to cycle to school every day for 5 years and after an 8 year gap i'm back in it.

Bought a Barracuda Jacana 20".

I bought this commuter kit out of argos as it had lights and a bike computer for a good price.

My question is how does it fit on my bike. The contents is the actual computer bit, a black sensor on the end of the wire coming from the computer and a magnetic black bit with a silver shield that goes round the black bit (sorry for the explanation, i'm sure some of you will understand what i mean), I know i bought from argos but it was cheap

Any help would be great, Russ

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David Lund

Surely it came with a setup manual?
The reciever sits on the inside of your fork leg next to the wheel and the magnet attaches to a spoke on the wheel, the distance has to be correct or it wont recieve correctly.
Then you need to set up the computer with the diameter of the wheel e.t.c
I dont know exactly how you do this as all computers are different.
Dave

russbelluk

David Lund wrote:

Surely it came with a setup manual?

Actually no, no instructions. i did get it to register a speed, but that was when the magnet was on the spoke like you said and i was waving the receiver past the magnet, but when i strap it to the fork i get no reading. I know you said about calibrating it with the wheel size but no instructions with it on how to do that. i suppose i'll have to play with it and see what i get, if nothing then i'll buy another (not a cheap one).

David Lund

Thats a bit stupid not having a manual, no wonder your lost. (thats Argos for you :roll: )
With the reciever make sure that its as close to the magnet as possible as it passes the leg, less than a cm usualy. Also keep them paralell with each other. you may need to pack it out with some leccy tape.
If your lucky the 26" wheel might be the default setting so maybe try and get it set up and drive next to a car and see if its roughly right.

If you can find a way to change it then measure the circumference of the wheel:

PI (3.14) X Diameter (side to side through axle)
= wheel circumference

Hope you understand all that
Dave

russbelluk

David Lund wrote:

Thats a bit stupid not having a manual, no wonder your lost. (thats Argos for you :roll: )
With the reciever make sure that its as close to the magnet as possible as it passes the leg, less than a cm usualy. Also keep them paralell with each other. you may need to pack it out with some leccy tape.
If your lucky the 26" wheel might be the default setting so maybe try and get it set up and drive next to a car and see if its roughly right.

If you can find a way to change it then measure the circumference of the wheel:

PI (3.14) X Diameter (side to side through axle)
= wheel circumference

Hope you understand all that
Dave

Cheers Dave, got it to work, not sure whether its calibrated for the speed though. I'll try either with the driving next to car or with 2 signs with distance on do the sum like that to see whether its right or not, Cheers again Dave.

Andy B

Most accurate way to get the wheel size correctly is to mark the tyre & the ground, then roll the wheel forwards one complete revolution & mark the ground when the mark on the tyre is at the bottom & measure the distance between the two marks on the ground. Input this measurement into the computer.

russbelluk

Andy_B wrote:

Most accurate way to get the wheel size correctly is to mark the tyre & the ground, then roll the wheel forwards one complete revolution & mark the ground when the mark on the tyre is at the bottom & measure the distance between the two marks on the ground. Input this measurement into the computer.

Good idea, i gotta work out what format its calibrated in.

whether you put in the measurement like you suggest or distance the magnet is from the contre of the wheel and so on, when its comes to calibrating, the scale is from 0 to 250, dunno whether that'll help

Andy B

The distance the magnet is from the hub has no relevance, all it does is count the wheel revolutions, wherever it is on the spoke it will always count one revolution.

The magnet will need to be ~3mm from the receiver on the fork to get the best reception.

I suspect that the computer is asking for the measurement in cm's if as you say it goes upto 250 (a 26 x 2.1 tyre is approx 2045mm if i remember right)

russbelluk

Andy_B wrote:

The distance the magnet is from the hub has no relevance, all it does is count the wheel revolutions, wherever it is on the spoke it will always count one revolution.

The magnet will need to be ~3mm from the receiver on the fork to get the best reception.

I suspect that the computer is asking for the measurement in cm's if as you say it goes upto 250 (a 26 x 2.1 tyre is approx 2045mm if i remember right)

Cheers Andy