I've never lived there and my opinion is overvalued at 2 cents, but I believe there is a very distinct Bay Area/ N. Cali style of handmade bicycle.
For the CR timeline lugged road bikes it's in the long points filed paper-thin w/ smooth filleted radii, some kind of fastback binder treatment on the seatstays, a 1-of-a-kind stem (perhaps a semi-threadless type stem that clamps on a plug thing on the steerer), and lots of weird custom machined frame bits.
Wait... you can't say that the style is "eclectic" ... _WHAT_ is it?
Exhibit A would be a bike described by Peter Johnson as his "works" bike for battling in Cat 1 crits in the 1970s. It was 15.5 lbs and entirely proprietary or heavily modified. That bike was stacked, and even had a full-on stem-adjusts-the-headset threadless headset.
Exhibit B is another precocious teenager's
http://oldmountainbikes.com/
Exhibit C - any touring bike or high-end tandem that would be only equaled a couple other places in the world
It's the tiny machine shops and lots of "tuning parts", the long haired tinkerers graduating through Uncle Al's framebuilding classes...I think that Al Eisentraut and Spence Wolf at the Cupertino bike shop affected most of the builders I'm talking about (PJ, Tom Ritchey, Bruce Gordon, Bernie Mikkelsen, Ed Litton, Charlie Cunningham, Joe Breeze, and others...), plus the local terrain (hilly and sometimes soaked) and the racing scene. I don't know, but I'd like to hear more.
Maybe the high tech industries nearby kept the talent around before or between building bikes. Also for decade after decade the very best eye candy was being imported to Bay Area shops, so the locals always knew how high the bar had been raised.
And about the mtn bike thing, since the topic is lurking somewhere here, I think that the local terrain (many smooth fast fire roads and double track) has brought a tradition of riding road bikes on dirt (!) and mtn bikes w/ road bike characteristics like drop bars. I'm getting in trouble now so I'll stop... just saying the lines blur - it's not like here on the CR list ;^)
I think the most kick-a** thing about the bay area builders is their make-it-yourself spirit. Lots of components were made integrally, constructeur-style. Where else would more than one builder be fabricating a 1-piece seatpost/rail/ and saddle combination? There is a proficiency - even from a guy's backyard shed - that superseded their contemporary European builders hands down IMO, whether it's bronze welding /fillet brazing, heat treating aluminum, and machining/casting/forging in very small runs, or just brazing "an italian-looking frame".
-jack bissell tucson, az
where our 4th Ave Bike Swap is saturday 4/1