Having a strange problem removing my chain ring bolt. problem is there is nothing to hold the back piece with because its perfectly rounded/flat, so when i turn the front the whole piece rotates. what do i do ?? All the ones ive seen have a slot so u can use a tool to hold it in place but mine doesnt. Thank you so much in advance.
The crankset you have is actually held together with rivets and not bolts. Some manufacturers of some low-end cranksets make the rivets with a hex head on one side. The easiest way to remove it is with a hex key and a drill. Select a drill bit that is slightly larger than the core of the rivet. Being sure to hold it steady with a hex key, drill enough material out of the back side of the rivet and it should come right out. Replace with a normal chain ring bolt and you're done.
(This is the easy way to remove most rivets. If you're working on a blind rivet - when you can't see the back side - start drilling at an angle. The trick is to mutilate the rivet but not the hole!)