In today's Palo Alto Daily News. Not a direct link (I can't figure out how to do that with their reader), so here's the text.
Illegal bike ban?
Dear Editor: Recently, it has come to the attention of the cycling community that Los Altos Hills has installed a stencil that says “NO BIKES” on El Monte Road Eastbound, just east of the Moody/Elena intersection. The town public works department indicated this was done at the direction of council due to safety issues.
Regardless of any good intentions of the town council, El Monte is not a freeway and cyclists cannot be prohibited from usage of that roadway per CVC 21960.
As such, this traffic device is illegal, and should be removed as soon as possible.
John Murphy , San Francisco