I can't see the hackle feathers in the pictures you posted.
Hens have spur buds too, and some hens do grow relatively large spurs over time. Hens of some breeds do have large legs too.
Have you heard it crow or gotten an egg from it? I might give it a few more days to be sure. It would be really frustrating to actually have a hen and go to great efforts to get rid of her!
I think Bielefelder mix is a good guess. I might guess the other parent is something like a Rhode Island Red or a Red Star sexlink or one of the other kinds that have a lot of red with a black or white tail.
There are many other combinations of breeds could also end up with that appearance, so those are definitely just guesses.
That picture is mislabeled somehow. A first-generation cross of Barred Rock and Rhode Island Red should be mostly black, with or without white barring depending on which parent was from which breed. There might be some gold or red in parts of it, but not the large areas of red/gold color that is seen in the photo. And the white leg color must come from another breed.
I agree your bird has a coloring similar to that picture, I just have a problem with how the picture is labeled.
