Mazda XCM




By Michael Gray (http://michaelgraydesign.wordpress.com)

The Mazda XCM is a cross-country mountain bike concept; which challenges the conventions of a triangulated frame with tubular front forks.

Control geometry is based upon a typical 29 inch cross-country bike, but with a unique design which takes advantage of the possibilities of composite-moulding technology, while eliminating high maintenance items such as external gears and hydraulic suspension dampeners.

While the idea of a mid-mounted internal gear-set is not entirely unique or new, and front swing-arms have existed on a relatively small number of motorcycles for some time, the Mazda XCM takes them and applies them somewhat differently.

The front swing-arm acts against a composite material leaf spring, as does the single-sided rear swing arm. These eliminate the need for hydraulic suspension dampeners, which typically require routine maintenance. This also saves on weight and overall complexity.

The mid-mounted internal gear set receives drive from the bottom bracket via a toothed belt. It then outputs to the rear wheel via a pinion and shaft, which are held and sealed inside the rear swing arm.

The steering is hydraulically controlled, running from a master inside the head tube to a slave inside the front of the front swing arm.

* The Eggbeater pedals used in the CAD model are the work of Brian Martina (downloaded from GrabCAD), while the Hayes Disc brake calipers used are the work of 'SG' (GrabCAD).