Patent Find: US 20140110208
If you want to know where bicycle development is heading, forget bike magazines and blogs that churn out industry-submitted press releases. Instead, become a patent observer and know about stuff months and years before things are being photographed at press camps. Use Google Patent Search and Google Alerts to follow the manufacturers you want to keep an eye on or to follow any invention relating to a particular area of interest. It’s as simple as that.
One such patent, which popped up in my Feedly stream today is SRAM's patent application US 20140110208 for a new freewheel hub design. We all used to ride bikes with quick-release axles until thru-axles grew axle diameters. In front 15mm has become the de facto standard with 20 and 24mm for gravity oriented usage. In the back, things have not been able to grow as much. Thru-axle rear hubs have been limited by design to 12mm. The limiting factor being the cassette, which needs to house a set of bearings on the inside and a tall set of splines on the outside.
In looking over SRAM’s patent, they managed to use a beefy axle by getting rid of the freewheel body altogether. The cassette sits directly on top of the axle thanks to two ball bearings and a nifty freewheel arrangement sandwiched between cassette and hub body. The freewheel mechanism is based on two flat coupling rings with a tooth systems facing one another to transmit torque from cassette to hub body. Advantages: room for big axles and larger diameter bearings, overall reduced weight and increased stiffness. Downside: cassette equipped with two bearings might get costlier than they already are.