Saw this bit of kit and thought, "That sounds to simple" but having decided I was not going to spend £100's on a bike specific Sat Nav decided to give it a go.
First thing I bought was a waterproof Sat Nav case/holder for my TomTom XL. Paid less than £20.
Then the next issue was how do I hear the instructions. Having used a car Sat Nav on the bike previous;y without sound I thought it would be great if I could hear the instructions rather than having to stare at the screen. Not much fun when navigating through a new city for the first time. Then I saw this advertised - Oreillette Air Tube
What a bit of kit ......... so simple.......... and works perfectly well. I could hear all instructions when volume was set at about 65-70% even when travelling on the motorway at about 100 MPH.
I appreciate its maybe not ideal having something stuck in your ear all day but
1) I would normally wear ear pops when out for a long run
2) I already owned a Sat nav and only had to spend an extra £35 - £40 for a case and the air tube.
I would highly recommend as a cheap option for Motorcycle Sat Nav.