Kappius Components: the death of the freehub?
We've seen in recent years how parts of the bike we hadn't considered can suddenly become the focus of development. The bottom bracket is a prime example. Sealed square taper units ruled for many years, then all of a sudden we had Hollowtech 2 and outboard bearings, we had press fit and BB30, we're just getting our head round BB386... that's a lot of design thinking going into two bearings and a tube. Will hubs be next? Kappius think so, and they're ahead of the the curve with a brand new system already in production.
Father and son team Russell and Brady Kappius are not happy with the current setup, and that's been the driving force behind the development of the Evolution hub. "I wouldn’t have moved forward with the Evolution hub if I didn’t firmly believe I could make a significant change for the better", says Russell in his design philosophy. So, what's to change?
Well the freehub, for all its ability to make the process of swapping cassettes a fairly simple process, places serious design limitations on the hub itself. Chief among them is the placement of the "wheel bearings” , which on the drive side of the rear wheel have to be inboard of the cassette, and in many cases that means they're even inside the wheel flange: almost on the centre line of the wheel itself. In an ideal world, says Kappius, the bearings would be as widely spaced as possible to make for a more stable load bearing structure. We've seen exactly that progression with bottom bracket bearings moving outwards to create a lighter, stiffer platform.
The freehub system also places constraints on the size and positioning of the drive transfer system; normally this is a tooth/pawl system and sits inboard of the cassette, again near the centre line of the wheel. The small diameter of the drive transfer system also means that it's transmitting very high loads, making it prone to failure.
"I'm very much a proponent of discs on all bikes, and am actually riding a Specialized Crux with BB7s right now, with my hubset," he says. "That said, I don't intend at this point to have a 130mm disc rear hub, but rather a 135mm. I'm betting that is where we end up once the 130/135 choice is made. And heck, I can interchange that wheel from the Crux to my Cannondale Flash 29er with just a cogset swap. But if it looks like frame manufacturers decide on the 130mm spacing for disc road wheels then I'll support it. It's pretty easy to do."
The major downside for now is the cost: at $999 with a drive cluster, it's a pricy thing indeed. But these are early days and small runs; assuming that the feedback is positive it'll be interesting to see whether the design principles in the Kappius hub get more widely adpopted. "Time for the bicycle hub to catch up with the other exciting cycling technological advancements", says Russell. Maybe he's right.bearing market will have a big improvince in the near future.I believe.
