Biking safety is more about your individual experience and ability than it is about having a critical mass of bikers (unless of course the critical mass is majority - as in Amsterdam).
How you ride your bike also depends on your personality - and how much you want your ride to be a videogame... Check out this video of a guy biking through NOLA:
http://www.vimeo.com/1918279
From my experience, paths that are physically separated from car's roads that are shared by pedestrians/roller bladers/joggers/baby strollers and bikers on it are not the safest place to be on a moving bicycle. The movement of a pedestrian is not predictable - they might suddenly stop - do a 180, cut in front of you, stoop to tie a shoelace. The skill level of some of the bikers on a path may be beginner (e.g. they do not understand the importance of riding predictable e.g in a straight line). If I do ride a bike on such a path, I'm riding slow and constantly saying 'On your left'. Predictability is very important (see this article about crossing streets in Rome) http://www.worldhum.com/how_to/item/cross_the_street_in_rome...)
Marked bike lanes that are on the side of roads are much safer. You still have to watch out for opening car doors and random-walk pedestrians (again!) but you have room to do evasive maneuvers.
In his book, J. Forester quotes a statistic that roadways are 2.6x safer for bikers than bike paths. Based on this study from Kaplan: http://www.bikexprt.com/research/synthesis/corvallis.htm#kap...
How you ride your bike also depends on your personality - and how much you want your ride to be a videogame... Check out this video of a guy biking through NOLA: http://www.vimeo.com/1918279
From my experience, paths that are physically separated from car's roads that are shared by pedestrians/roller bladers/joggers/baby strollers and bikers on it are not the safest place to be on a moving bicycle. The movement of a pedestrian is not predictable - they might suddenly stop - do a 180, cut in front of you, stoop to tie a shoelace. The skill level of some of the bikers on a path may be beginner (e.g. they do not understand the importance of riding predictable e.g in a straight line). If I do ride a bike on such a path, I'm riding slow and constantly saying 'On your left'. Predictability is very important (see this article about crossing streets in Rome) http://www.worldhum.com/how_to/item/cross_the_street_in_rome...)
Marked bike lanes that are on the side of roads are much safer. You still have to watch out for opening car doors and random-walk pedestrians (again!) but you have room to do evasive maneuvers.