Just a quick update problem solved at least to my satisfaction. :yahoo:
Here's a picture of the setup that works for my gps.Nuvi 780
Jabra 210 bluetooth dongle plugged into the headset output of the Nuvi 780 through a 2.5 mm to 3.5 mm headphone adapter and paired with scala rider q2, mobile phone (iphone) paired with nuvi 780 through bluetooth.
Cons,
MP3 in mono but as the scala rider Q2 only supports this mode over bluetooth not too much of a loss. Also the scala rider helmet speakers suck so if the quality was better coming from the Jabra I probably would not be able to tell.
There was some echo on one of the phone calls made from the helmet to my wife's mobile but it seemed to disappear when the microphone was moved up in the helmet.
In a totally quiet situation there was some clicking and background hiss heard through the helmet speakers. note the volume was turned up high and in an area of high radio traffic, ie wireless lans, bluetooth equipped vehicles etc. - not noticeable when directions or music playing.
Something else to charge at night.
Another non waterproof piece of equipment to put somewhere
Pros,
Under $230 invested total. nuvi $178 from Amazon, Jabra 210 $37 from Amazon, headset adapter $1.63 from RadioShack although I have a more elegant one on order for $10 Amazon.
But I will need mounts and waterproof box.
The Jabra bluetooth dongle connects each time with no intervention ie the pairing seems to be very good no repairing needed so far.
Quite a small and easy setup
Really clear audio( at least phone and directions from the gps to the scala rider headset) also the phone calls to a landline were clear as a normal mobile conversation.
No permanent changes to any equipment so no warranties voided
Phone integration is no affected, ie you get dialing via voice or touchscreen as per normal
Can be adapted for any type of gps
IF it has a headphone socket output or connections for an external speaker.
Uses my existing GPS.
Yeah I know it's redneck engineering. But it did not take long and no soldering or hacking together pieces, just plug and pray.
Yes I know it's easier and better to buy the Zumo but in the line of farkles this one is down the list after Givi and GP suspension.
Hope this helps, maybe not, but it was fun trying to solve the problem.
DB