Originally Posted by folder fanatic

If you are taking a compact folding bike, you can take it with you on buses or trains providing you cover it up with a soft bag of some sort. see: http://www.metro.net/

I have taken my smaller compact Dahons and the Brompton with me if they are folded up during rush hour period. I just treat it like luggage when in the passenger areas. Just as long as you do not block the aisles or run over someone's foot, I never had any problems with any of my bikes. I use all rail systems in Southern California.