Motorola S9-HD very bad connection with my iphone 4s when riding my bike

When I ride my bike with my iphone mounted on my handlebars and try to listen to music, the S9-HD cuts in and out A LOT. I have tried re-pairing, and rebooting both. I don't think it is a proiximity or interferance issue as I recently tested in packed (ie, lots of other bluetooth) Starbucks and walked 50 ft away from the iphone with no issue. I've heard of sweat issues, but I don't think this is it as it starts immediately when I start riding. The problem really only happens when I am riding.

Any suggestions will be greatly appreciated.