Re: what did you do to your motor bike today?
That strap is a generic "fits all" one for anchoring the arm on a coaster brake rear hub. It will work fine for the drum brake too. Just remember that the arm will want to swing forward when you apply the brake.
My idea FWIW: Have one end of the strap wrapped around the fork leg, squeezed tight with a bolt, and the other, loose end, of the strap pointing forward and anchored to the drum arm with another bolt.
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