Weird speedo - help

[Oboscribe]

Hello all
MY 2012 650 is causing me a headache. I've had it for 1500 miles and it's great, then went to Scotland last weekend....
Thirty miles of rain up the M6, and the speedo started fluctuating random speed figures, which gradually reduced until it was showing zero, and the odometer/trips stopped recording.
Two days of dry weather followed, and still no speedometer readings.
Heavy rain the next day, and I got a perfectly functioning speedometer and odometers for about twenty miles, then lost them again for the remainder of the trip.
The forum threads here lead me to believe the front wheel drives the signal for the speedometer.
I've had the connection apart from the front wheel sensor (a bitch to access) and put it back together. I raised the front wheel off the floor, and spun the wheel, speedometer continues to read zero.
I spun the rear wheel out of curiosity, and got a speedometer reading.
I haven't ridden the bike on the road to see how long the speedometer works for (yet).
As an aside, there has been no ABS fault showing at any point, and the ABS has been tested deliberately by braking and is working correctly.
Any thoughts/advice would be appreciated.
Cheers.

[wurzel]

Someone with direct knowledge of your bike will be along soon, but the speedo drive probably comes from the output shaft to the front sprocket, if you can find it, clean and dry it, and it's conections, you might find your sorted, protect it with something like ac50, it's good stuff for the conectors blocks.
I hope this helps.

[SuzukiSte]

speedo drive pickup comes from in front of the front sprocket.

[Oboscribe]

OK blokes, this helps makes sense of it all. I've had another look based on this info, and there is a sensor at the sprocket which I have cleaned up, along with the connector to it. We'll see if it has had an effect. At least I know which bits to play with now! I'm old school, and have never had a bike that drove the speedo off anything other than the front wheel ( or gearbox on my Ural) hence my confusion with ABS sensors.

[Oboscribe]

Update
Took the bike to work yesterday - 60 miles round trip, the speedo worked perfectly throughout. It was a dry day, so there is still a bit of doubt about what will happen when it gets wet - but it's all good so far.
Thanks for the advice.