Originally Posted by
TMonk
back on topic: I'll second
Bald Paul and say that terrain really matters. San Diego is "slow" because it's hilly, windy, and has a good amount of intersections to deal with, until you get further out east. And the pavement is in really crappy shape in most places, except the fancier neighborhoods.
I was keeping up with traffic going down Linda Vista Rd towards the ocean back in the late 1980's, probably in the mid 40 mph zone, then later realized I'd have been toast if someone hit me. And I've never been slower than while climbing Texas St. from out of Mission Valley into the Normal Heights area. I don't know if I could walk my bike up that hill now (15% IIRC, live in the PNW now), but I'm getting back into it, so hope to build the strength and stamina up again.