The Co-Wheel is a retrofit wheel for bicycles made joining 2 standard bike wheels together. It has the advantage of preventing tires from ending up in the tram tracks and, if punctured, can still get you to your destination on the bicycle. Its double tires layout takes to better grip on roads, especially on wet or snowy slopes, and to a very long tire tread life span. The safety is derived from the width of the dual tires that, when inflated, bring the cross-spokes of the wheel into elastic tension, according to the Co-Wheel patent. This solution gives to the Co-Wheel a superior comfort that comes from the split rim. The retrofit wheel is actually a copyrighted conceptual ready-made, meaning a self-producible piece made of cycling components that are commercially available and that everyone can easily obtain. One prototype have been successfully tested for more than 20,000 km.