Anywhere in the Bay Area have 18t cogs for a friggin' Langster? I want to put 'em on both sides of my flipflop, it has the 16t on the freewheel side now, but I think I need to gear down and work on leg speed. Or a 17 and an 18 would be sweet. Do I have to make the pilgrimage to American Cyclery up in the Haight?