If you want to add spikes to your biker jacket, all you need to do is buy a package of screwable spikes. Take either a special leather cutter, or even just a pocket knife, and cut your holes into the spots you want the spikes, such as around the sleeves. Don’t make the holes too big, but they can’t be too small either or the spikes won’t fit. Simply push the screw part up through the hole, and then screw on the spike. For a video tutorial, check out HedgeTV on YouTube.