Welcome to the forum Firetrail,
The one shop I like going to is BikeNut in San Francisco...it's a boutique shop with lots of highend gear and parts. I'm a regular customer and enjoy going there every chance I get. It's located in the Marina district.
(Click here for location
) Huseyin and staff are great and will treat you well. Highly recommend for lightweight parts!
I am in no way affiliated with them but I just wanted to praise them for all the great customer service I received. And plus, they're all a bunch of likable guys too.