Acually you may beable to unbolt the large outer chainring and it will leave a single chainring. You may not need to redish your wheel either, since those 1pc chainrings come in alot. Basically just pull off your 5speed freewheel and replace it with a bmx freewheel. Rip off the gearing things and shorten your chain. A bmx cog is what, 10-15$? You may want to buy a chain tool while your at it.