I have two of these trailers (a black one and a yellow one)(unfortunately not quite the same color of yellow as the Smart Car) and they both came with standard 1 1/4 receivers to fit the standard 1 1/4 receiver hitch on my bikes. I assume they could not fit a standard receiver hitch on your Harley for some reason so they came up with something else. The Smart Car hitch will be a standard 1 1/4 receiver hitch. So just call N-line and ask for their standard 1 1/4 receiver (part attached to your bike in some manner). What I am concerned about though is that the receiver comes straight out the hitch so with the Curtis hitch it may be too low. The more expensive hitch that is available may be about right height. If this turns out to be true then I will ask N-line to fabricate a receiver that angles up. Or possibly buy the more expensive hitch. If your bike does have a 1 1/4 receiver on it then you don't have a problem at all. Just pull it off your bike and plug it into the car.