After assembling ten outriders (1 chap, 9 outriders), I have a suggestion to save others some trouble.
From what I can tell, GW is molding their new kits to rather high tolerances that a layer of primer/paint is enough to throw off how things are supposed to go together. The outrider bike is one in particular.
So prior to assembling, I suggest that you carefully drill out all of the holes with a 3/32"(for the smaller holes) and a 5/32" (for the larger holes) drill bit by hand or drill vice.