I've noticed the same, the only time I can ever "keep up" with the green lights on my folding Dahon is on 5th ave, the very down-hill portion from 40th street t

I've noticed the same, the only time I can ever "keep up" with the green lights on my folding Dahon is on 5th ave, the very down-hill portion from 40th street to about 23rd. That's a nice stretch. 7th Avenue between 59th and 48th is also pretty nice hill-wise (assuming the traffic isn't insane).