You're asking a specific So Cal question and there's a specific forum for that if you have any more So Cal questions. Helens is good. If Performance is closer (5th and Broadway), try them.

If you don't mind an opinion, you sound like you may be a bit of a wobbly rider. I suggest you avoid PCH at all costs because it's extremely dangerous. I realize you have no choice but to ride through that one narrowed location you described, but it's not like there's zero room there. Also, if you're going southbound, there's tons of cars parked and often times there's no room at all. Weekend drivers are among the worst along PCH, so why risk dealing with their distracted (girls) sun blinded beer fog vision? Stick to the beach bike path, where the dangers are less.