even a month ago, I would have related to this - I was so afraid of being clipped in a standing, that I would fall and not catch myself because I was clipped in. I have absolutely no idea how or when it happened; I wasn't practicing or trying to stand, but I can do it now with no problems, and for quite a distance. I don't think I tried to do it that much before because I read that it's hard on the knees, so why would I bother??? But when I got a weekend job as a group ride leader, I started doing it as a ways for me to go uphills at a slower pace when I was riding sweep so I could stay back with the slower riders. I know it sounds crazy, but I don't have a really low gear on my CX bike, so spinning for me makes me go faster than those spinning up in a granny gear - and I can only spin so slow (any slower and I would fall over; the gear is just too big to spin "freely"). If I grab a couple gears and stand, I can ride a little slower just going from side to side...I'm stable standing up, and it doesn't take as much pressure from me to pedal because I'm using gravity (rather than spinning and using my own muscles). And, I found that, at least for me, it doesn't hurt my knees. Ever since I "discovered" I could do it, I started doing it more on my own or in my faster group rides, and find I can get up hills a lot better than I used to.