The BAM one is supposedly 1/56th, though I haven't checked the dimensions. I do have the BTD one as well and the difference in size with BAM is huge, no way these could be passed off as the same bike model on the same table. It's a very clean cast though and looks a lot easier to assemble (and hold together) than the BTD one.
Artizan also has one and I'd be interested to know how it scales out as it comes with various crew sets.