Cycle computers

[Dave]

Can you help?

I wanted to fit a cycle computer as my VDO Speedo waves around like a puppy’s tail.

Two choices wire less, no good due to the Hf flying around the engine bay so it’s a Rally wire one  £10 from “Argoos” that’ll do me jimmy.

I fitted the sensor to a cycle wing bracket and small magnet to the inside of the rim tested it and every thing worked ok, but the wire was not long enough to mount the computer on the dash.

I then cut the wire to extend it but its very strange, there are two un-insinuated multi strand wires which look like they are shrouds against interference but the middle only contains a fibreglass material?? One of the wires looks like it has a thin red lacquer applied to it so I thought that was insulating one from the other.

Tried to solder the extension wire in but the computer doesn’t work?

Tried to rejoin the original wire in but it doesn’t work?

Any ideas boys.

     

[Blatman]

Never done it myself, but have a look here.

[steppenwolf]

The 'glass fibre material' is there for strength only. Only two connections are required to complete the circuit as the magnet simply closed a magnetic 'reed' switch.

Back to basics then:-

Very carefully strip back some more of the outer pvc sleeve to try and determine what is going on. If that doesn't indicate the actual wires to use, :-

Using a continuity tester or test meter set to resistance, try all permutations of pairs of wires and bring the magnet next to and then away from the sensor to see if the tester indicates a circuit - if it does then you have located the two required wires and can match them up with those on the other piece of cable. If you cannot get a completed circuit then you may have damaged reed switch sensor, in which case you are probably down by £10.00 ....

[Westfieldman]

Get one from a cycle shop that works on the rear wheel the cable is longer

Paul.

[stu999]

Or, errr, fix the VDO speedo. If it is electronic type, it is more than likely that the sender only requires adjustment. If it is erratic all the time, try moving it slightly closer to the lobro bolts/prop. if it is only playing up above a certain speed, try moving it away slightly. 0.5mm can make a huge difference to the way your speedo behaves.

If it is cable type, it may be that the cable itself is on its last legs.

Unless you have already tryed all that, then just ignore me

Stu.

[Dave]

Thanks lad’s

I have sorted it now, turns out the 2 wires from the sender are coated in a very thin clear high temperature insulation, this was stopping the solder from making a good contact. Just burnt off the insulation with a match and re-soldered the joints works fine now.

Ta