Shimano 105 Triple Hollowtech II review
Born of the original BMX crank configuration, Shimano started the revolution to the current two-piece crank systems with its Dura-Ace model and the design was soon fed down to the other groupsets. The left-hand crank is secured using a pair of bolts that must be tightened carefully using a torque wrench, though plastic spacers are present to prevent inadvertedly overtightening.
The 105 arms are less hollow than the costlier Ultegra and 157g heavier Dura-Ace versions and the chainrings are stamped out rather than machined – the smallest one is steel. The teeth are perhaps less radically profiled than those of the Deore chainset but they still ramp very smoothly under pressure. In our experience these pressed chainrings don’t last as long as machined ones, but they can be replaced with other brands or Ultegra or Dura Ace.