bottom bracket bafang bbs03

Hi, I`m about to order the Bafang BBS03 1000w motor-kit on e-bay. The kit`s come with 68/100/120mm bottom bracket sizes. My bike: Cube Reaction GTC Pro 2011 mod. I cant seem to find the bottom bracket size for mye bike. I know the bottom bracket is bigger than a normal bike, but I dont know how...