Well, i got bored today, so ripped the Cateye Velo 8 out of the spares draw and fitted it up to the 29'er.. works good! still playing with wheel measurements but she is 95% spot on...
The sensor is a screw in magnet type(OME from cateye) the pickup sensor has been ziptied in place through the fork shroud, nice and stable, nice and close..
The speedo itself is mounted inbetween the tripple clamps.. a little bit of dbl sided tape ensures it wont go walkabout over the rough stuff...

The Large dispaly and features are good and give an accurate read-out on riding time, distance covered both in total and per ride, max speed, Avr. speed, 12/24 hr clock. Not a bad purchase for $35.. Next is Li-po halogens Lights

Sorry about the quality of the pics, the camera had flat batteries and the ol mobile phone was the next best thing!