I ride a long wheel based recumbent which has a long exposed chain which is a problem when I wear long pants so I use one of those short and very thin bungee cords and just wrap it around my leg.
I was once stopped at a stop sign with my right pedal up as usual and when I started the down stroke my pants got caught in the chain. I had only just started and both pedals were off the street so there was nothing for it but simply to flop over (fortunately I'm not far from the ground). I didn't get hurt but felt stupid as there were people watching, looking at me like I was simply inept when I really am ept normally.