I have a front end shimmy at low speeds that only happens occasionally, it seems to be triggered by the ruts or seams in the road and only happens at low speed between 20 and 30-35. It pulls the handle bars back and forth, first just a little, and then the shake builds to a shimmy, so I brake hard and it stops. I cannot feel a problem with front wheel bearings, so then what? Maybe fork bearings? Any input will be appreciated. Jim