After deliberating for a while Boulder has decided to let ebikes go pretty much
anywhere bicycles are allowed. The article mentions that ebikes will not be
allowed on "open space" trails which are dirt tracks meant mostly for hiking
and mountain biking. This is a very common-sense restriction. I wouldn't even
want to take an ebike on one of those trails.
http://www.dailycamera.com/news/boulder/ci_24414442/boulder-council-approves-e-bike-pilot-program