I just converted my cruiser to a Nexus 7. Select 4th gear. Loosen the cable and remove it from the shifter linkage at the hub, then remove the coaster brake torque arm nut & bolt. From there it's the same as any fixed speed. Put it back on in the reverse order. I like to turn the sprocket until the lock nuts line up with the slots in the dropouts. Make sure all the little yellow marks line up on the shifter mechanism, then put the bolt in the brake arm strap and put the chain on the sprocket. Center the wheel with the correct chain tension, then tighten everything down. Last thing is to recheck the yellow marks , and the shifter--- it has to be in 4th gear. Reattach the shifter cable and take out any slack. There are probably Youtube videos that show the whole thing.