Fat bike funthe double double 30 is 26 inches of fat tire fun a true fat bike with 80mm drilled out rims and 26 x 4 tires these bikes can roll over anything in any conditions the double doubles frame is made from aluminum with a custom hydroform fork the double double 30 flattens the inclines with shimanos 20 speed xt shifters and stops on the declines with deore disc brakes one of best fatbike39s of 2015 click on the image above to read more about bike radars39s write up in the