Hi there all!

Like some of us have already, I installed a bike computer some time ago and have found it very useful particularly as an aid to remembering when to fill up!

However, I had to change the front disk and when transferring the magnet onto the new disk I mis-aligned the sensor and to cut a long story short - well and truly boogerd the sensor.

Now I had never given much thought as to what the sensor was made from - just that as long as it was near a magnet - then it would measure the speed etc.  I

It turns out the sensor is non other than a switch - a type being toggled on and off by a magnet - known as a magnetic reed switch.  These can be got for pennies at an electronics part shop - however there is the issue of encapsulating the sensor ready for mounting and of bringing the contacts out on wires for connection to the bike computer.

Whilst not insurmountable, a more ready made solution already exists in the form of home security alarm door contacts.  These are usually sold with two parts - a magnetic sensor and a reed switch.  They come in their own resin filled mounting with terminating wires pre-soldered.

I cut the wire leading to the original (boogered) sensor - stripped and bared two wires and connected them (after routing round the bike frame) to the new sensor.  The sensor itself can be tie-wrapped to the front fork leg.