 Oversized aluminium axle on L/H crank |
 Separate spider |
The benefits of having a hole through the centre of a crank arm are the same as those to be had from having one through a frame tube. The only significant problem is how to get the hole where it is needed.
Innovative component manufacturer Rotor does it by drilling and, in the case of the 3D crankset used to great effect in the Tour de France by Cervelo TestTeam’s Green Jersey winner Thor Hushovd, by drilling a total of three holes the length of each crank.
The 3D crank is currently still under development. Rotor’s first foray into the world of hollow crank manufacture, also used by Cervelo TestTeam, was named Agilis and, in Evo guise, is available now. Its ‘Hollowminium II’ technology employs just the one hole, which is drilled from the bottom bracket axle end of the crank and runs through the axle orifice to stop short of the pedal axle thread.
 Extractor cap on R/H crank |
 L/H crank takes up play |
The hole left in the back of the crank is plugged with what Rotor calls an ‘aesthetic’ bolt that certainly gives the whole assembly an intriguingly high-tech appearance. It complements the delicate CNC-machined lines of the crank arm and spider and is in turn matched by the precision machining of the crank caps.
 Aesthetic bolt |
 Note ‘O’ ring |
These have distinct functions: the cap on the left hand crank is used to take up free play in the bearing, while the right-hand cap extracts the crank from the oversized aluminium axle. This is designed to fit any Shimano Hollowtech II pattern bottom bracket bearing assembly, which includes Rotor’s own Self Aligning Bottom Bracket. ‘O’rings ensure a snug fit for the axle.
£220 including integrated bottom bracket axle, crank lengths 170, 172.5 and 175mm, compact or 130mm BCD, optional red anodized spider.
Road test coming soon.
