Took my first long ride today on the new swamp lites. I have a shimmy in the handlebars at any speed above 20-25mph. This is on pavement, didn't seem to notice as much in the dirt. It's a very rythmic pattern to the shimmy. Suspect tire balance. Is there anything else I should be checking for? Would I lose air if a bead wasn't set properly? Could toe adjustment cause this? Thanks for any thoughts, Tim