So I have a 27" wheeled bike which I want to make single speed, but retro stuff is new to me as I'm used to modern I'm getting a new wheelset, but all 27" wheels are freewheel. Would the below cog work? http://www.ebay.co.uk/itm/BMX-MOUNT...sure_cycling_bikeparts_SR&hash=item2c624f5336 Any help will be appreciated. Thanks. EDIT: Would it run straight away if I screw on the cog and be aligned okay, or will I have to re-dish and re-space the wheel?