Shimano CX70 chainset & front mech review
The rise of cyclo-cross, especially in the US, has led to an increase in the number of dedicated components available. Arriving fashionably late to the party, Shimano have launched some 105- and Ultegra-based ’cross specific parts which should appeal to those looking to upgrade.
The CX70 chainset and front mech are both finished in Ultegra grey, with a glossy spine on the cranks that should shrug off heel abrasions. Sharing Shimano’s Hollowtech II crank and 24mm hollow axle design with its roadgoing relation provides a great combination of rigidity and light weight.
The 36/46-tooth Hyperdrive SG-X chainrings are shaped and profiled to work best with Shimano’s directional 10-speed road chains, giving increased surface contact for improved power transfer, but will work with nine- or eight-speed setups.
The front mech can handle a 16-tooth capacity and its shape is optimised for 46-52t outer rings. A wide forged outer link gives the shifter cage greater rigidity, for more positive actuation, and in use shifting is markedly sharper than previous mountain bike-derived mechs.
Replacing an old square-taper bottom bracket and converted mountain bike chainset with the CX70 chainset and compatible bottom bracket saved 184g, and the clamp-on front mech shaved another 27g. But performance is key, and the Shimano parts excel.
The wider spaced bearings and hollow axle give a solid platform for exploiting the stiffness of the cranks, and the effect is immediate acceleration, perfect for heaving over steep rises or out of slow corners. Even our ham-fisted, under pressure, race day gear changes couldn’t upset the CX70.
Under full load, the swift shifting mech and outer chainring with its four sets of machined ramps eased shifting to the extent that we didn’t need to ease off as much while changing gear, so could get the power down sooner.
The chainset is available in four crank lengths, and the mech in top or bottom swing, with clamp-on or braze-on fittings. With the matching CX70 brakes and Shimano’s extensive parts catalogue, accelerating your cyclo-cross ambitions just became easier.
This article was originally published in Cycling Plus magazine.