if your chains going round when your not pedaling you have front free wheel (ffw) free hub has a rachet mechanisam like a rachet you'd put a socket on and un do a nut with, where you can tighten the stroke back and tighten again, or loosen, this is the same as pedal kicking, allows you to kick forward then back stoke from the gap the ratchet allows it to go back with your feet, a ffw is the same but its on your cranks, when using a rear free hub which you dont have, you need a front fixed sprocket, look on tartybikes, look at a free hub 135mm width axle or 116 neither matter, by the way if you are riding a mod your rear axle spacing will be 116mm anyway yerr when you look at a fixed hub it will be the hub shell level from flange to flange, a freehub needs room for the mechanisam thats why when you look at a pro2 or chris king hub the side which the sprocket is there is a rise on the side of the sprocket in between the flanges for your spokes, a freehub you can spin and hold the sprocket and it'll click, a fixed hub wont it because the sprocket is fixed to the hub and is designed not to move