Re: single speed bike converts to multi speed?
They sell derailleur adapters for coaster brake and fixed gear frames dropouts. Just look on ebay. If you can bend the rear end apart more you can do it. Disc brake adapters can also be found on ebay. Caliper brakes for 26 in cruiser frames are easy to find at streetlowrider.com or bikepartsusa.com. So the answer is Yes if its worth the trouble for you sure you can.