Bobsled/luge runners

Do the runners of a bobsled/luge (the metal parts in contact with the ice) have sharp edges like an ice skate, or are the rounded/smooth? It seems like bobsleds have only a very tiny degree of steering control, routinely bumping into the sides of the track. On occasion they get a little bit sideways, but the runners don’t kick up any ice shavings, suggesting no sharp edges. If not, why not? Would they really slow the sled down that much? Couldn’t you still have a broad area for contact with the ice to minimize running friction, but still have sharp edges to provide a greater degree of control than they currently have?

Luge sleds have sharp, ice-skate like blades, while bobsleds and skeleton sled runners are rounded.

It’s my understanding that sharp blades are faster, but harder to steer (harder as in it requires a great deal of skill; it’s not physically difficult - in fact the tiniest movement or shift in weight can throw you way off course).