Reviewed by Brian Mullin http://www.gramslightbikes.com/
I have been testing a set of the Race Face SIXC (silent C) cranks for almost 2 months now, and they have proven to be stiff, durable, have been good shifting, and are made of uber bling carbon fiber. The SIXC cranks are made with their Optimized Carbon Technology program, and have been created for All Mountain biking, so they are slightly overbuilt in comparison to the usual carbon cranks. They are strong enough for mellow freeride, but light enough to appease a weight weenie (like me) or a cross country rider.
In a nutshell: carbon fiber is a high strength, high stiffness material that when combined with a resin matrix creates a composite with exceptional mechanical properties!
Race Face SIXC Cranks
The crankset has an external bottom bracket, aluminum chainrings, carbon arms, and a CNC CrMo spindle, which is molded onto the drive side arm, and includes their spline “EXI” interface for the non drive arm. The SIXC all carbon composite arms are engineered and manufactured in their British Columbia factory, and are hollowed out, with the unneeded material removed from the core, and offer exceptional strength to weight ratio. I tested a 175 mm set in the 22/32/bashguard version (they come in double and triple configurations), and it weighed in at 752.1 grams, including the arm end covers (pedal boots).
Measured Specs (175mm):
Bottom bracket – 94.9 grams
Spacers – 1.3 grams (each)
Drive arm, spindle, chainrings – 457.7 grams
Non drive arm – 179.6 grams
Pedal washers – 2.5 grams
Pedal boot covers – 16.1 grams
Total – 752.1 grams
The EXI interface external bottom bracket system is easy to install or remove with standard tools, and has a fully adjustable chainline. There are multiple spacers to adjust for different bottom bracket widths and front derailer types, with micro spacers for exact fine tuning of the chainline if required. The bearing cups are triple wiper sealed, and the bearings are filled with Phil Wood grease. Installation was very straight forward, put on the bottom bracket, slide the drive side arm with its spindle into the BB, mesh the other arm on and tighten down with the 8mm bolt.