A roller for a roller grinder, the roller including a shaft and a grinding shell in the form of a tubular sleeve and having an inner face to be retained around the shaft. The roller grinder is characterized in that the shaft includes two shaft parts, each shaft part having a respective inner end portion, wherein the inner end portions are arranged to be positioned facing each other and include coupling portions arranged to couple the inner end portions of the respective shaft parts to each other, thereby forming the shaft. The disclosure further relates to a method for assembling a roller for a roller grinder, the roller including a shaft and a grinding shell in the form of a tubular sleeve and having an inner face to be retained around the shaft.