I have a hard rock. I think mine is a little older. I used an angle grinder on the drop outs to make them horizontal. there was some metal between the drop out and a gap behind it. Anyways it is the smoothest, nicest single speed I have ever ridden. I commuted with it to work for a few years until my son took it from me as his (the bike was a little small for me). I think you will like it, the components on mine are really good quality.

FYI on mine you can take the rear cogs apart and just add your single speed cog with some spacers which I took out of the 5 gears that were back there.