Shimano 105 5800 11 speed double chainset black there are several chainset options for the new 105 including the fc 5800 a new four arm hollowtech ii design similar to that of current ultegra and dura ace its stiffer and lighter than the five arm design it replaces and shimano has reinforced construction around the chainring area to further improve the stiffness to weight ratio the chainset uses the same bolt circle diameter for compact and traditional double chainsets which means one crank