I had the same on my 09 Sporty. Bloody odd noise when at low speed (but not all the time either) and then it would disappear at motorway speeds etc.
Front wheel bearing was shot to chit! Somewhere in the past a previous owner must have been over zealous with the power washer and got water into the bearings or perhaps they were light on grease in the first place. Either way took the rim to dealer and they swapped out the bearings for about $100 all up - showed me the old ones and they were buggered!