Originally Posted by Slash5

Googling around the dropout is normal for that bike - didn't really find an answer other than just because.
You can replace the axle with a hollow quick release axle if you can find cones that match - they have to be replaced at the same time. I've done it on generic replacement wheels before.

Originally Posted by gugie

I never understood those dropouts. You find them on a few other frames out of Japan. It gives you the look of a horizontal dropout without the functionality. Shoulda just gone with vertical dropouts, IMO. I took a grinder and a file to one of my daughter's bikes, which was an old Hardrock as well, since I was converting it to an 8 speed Nexus IGH, and needed the ability to adjust chain tension.