They both go both ways bit Cleo does seem to slightly prefer one way than the other. It maybe that she prefers to face her nest so she can run straight to it? Recently I forgot to oil Cleo's wodent wheel after cleaning & we could hear it squeaking from another room. It had a different squeak when she changed directions & ran the other way
We watched her on the camera to check if that's what the slight change in noise was & it was that!