Uncle Phil said:
Do you have a guard on your chainrings, BM? My 'bent doesn't. I rarely ride it in town, but it sometimes worries me that if I were to hit a pedestrian with the teeth of the big chainring, it could make a bit of a mess.
A nutty bloke came to one of our roadshows in Wolverhampton, and berated Ian Fardoe for his recumbent, because he reckoned the chainring was dangerous. He said that cars were safe, because they were designed so that a pedestrian would just roll off the bonnet, if hit...
I've never seen it tested, but I wonder how much difference it would make. If the chainring were not revolving, then I don't think you could actually stab someone with it, and if it were, then the cranks and pedals and momentum would come into it anyway. I suspect the ring is to protect the chainring, as much as anything else.
That said, I've done the old tripping over my own chainring thing on the trike...