Confused by bone rotation

I’m probably just being a dumbass but… I’m in pose mode (2.57.1). I select a bone. I set the transform rotation to XYZ Euler. I hit ‘r’ and ‘x’ to rotate the bone on it’s X-axis. As I rotate, the Y, and Z components also change. Why? I very definitely do NOT want the other two axes changed? If I ‘manually’ set the X-rotation to exactly what I need it seems to perform exactly the same roration, but the Y, and Z components stay locked at zero (what I wanted). Locking the Y&Z axes also works, but both the latter two methods are a lot more effort than just unsg ‘r’+‘x’. Can someone un-confuse me? Ross.

thats how it works
but if you hit n or view/properties you can click and drag directly in the transformation panel, might be a little quicker.
Also its common practice to lock certain bones before animation it might take longer to set up but it pays in the long run.

Thanks sx-1. Your reply made me go back and look again. The problem was the bone in question had picked up some roll. So the rotate was picking up Y and Z components. I had to clear the roll on it, and several of its children. I just didn’t think to check. Ross.