About a month ago I heard and FELT my front wheel like click and grab a little, I though nothing of it at the time thinking I may have run something over. Last week it dit it again, only this time instad of 2 click, grabs it felt like 5-6. The best way to describe it is like the wheel was stuck for a sec. Both times were at average speed (25-30 mph). I dont wheelie this bike, the triple tree nut is secure, the brakes werent rubbing, until this occurred, now they are. I did not grab the brake at any time when I felt the clicks, they just happened while riding normally, and I heard the click sound as well as felt it in my hands...

 

Most likely your wheel bearings. Mine went out on my f3. Sounded almost like grinding brakes? Take off the wheel and check the inside for bad bearings or metal dust. Note the #'s on the bearing seals so you can get new bearings from a supplier for a lot cheaper than a dealership.