Its not a flip flop hub, I simply removed the original hub (seven gear cassette) which came with the bike & ditched it, I bought a new hub with disk break mount for ease of attaching the drive sprocket (standard pocket bike sprocket & theres heaps of different gearing available as they race these bikes on different tracks and they are always changing the gearing, so this makes it great for fine tuning) I had to machine out the center of the sprocket & drill the six mounting points thats all, I had to purchase a hub which gave me the same width as the original hub & could only do this buy purchasing one which was for a slide on gear cassette, I then simply machined the first spacer which went over the hub & threaded one end for the freewheler to screw onto & then machined another spacer to put in front of this to give me the width I was after, thats it. you could quite easily turn the pull start around so to be able to pull start while sitting on the seat, but I put it back to its original position as its got that much compression I could not crank it over, believe me you need to rest one hand on the seat & get an nice strong stance and yank, I am hoping that after its run in it might be a lot easier to pull start & then I will try starting it from the seated position, hope this makes sense