I have to wonder if there is another factor at work here, which is familiarity, or lack thereof. I dislike cycling in suburbs - period - but Walnut Creek does have the iron horse trail running the full north-south length (and much further beyond) which intersects the contra costa canal trail which runs roughly in a half loop from concord down towards Walnut Creek and back up, intersecting several other bikeways. in fact, one could ride from more or less the middle of concord to Walnut Creek Bart almost entirely on a fully separated bikeway, put your bike on a train and be in any of a dozen cities full of even more bike lanes and great bikeways. Besides the iron horse and canal bikeways, there are lots of bike lanes in Walnut Creek, and while the burbs are not my cup of tea, the PfB bike raring for Walnut Creek is probably pretty accurate at 37/100, crappy but significantly higher than most cities in California, like Los Angeles, San Diego, or Carlsbad, but much, much lower than the handful of California cities which have truly committed to bike infrastructure like Berkeley, San Francisco, or Davis.