The rotor rex 11 x1 76bcd chainset uses the trinity drilling system technology which helps reduce weight and maximize stiffness rex is the new mountain bike crank line from rotor this additional line with its own designation and design will help to clearly distinguish the rotor mtb from the road crank line the rex 11 crank the first number indicates the level 1 being the highest and the second number indicates the number of rings in this case it is 1 single chainring the new qx1 narro