Russ Kappius, an avid mountain biker, is interested in bike hubs. So much so that around four years ago he wanted to design one that would give more speed and responsiveness for the rider.
After seeing a demo part from a major manufacturer that gave him an idea for an oversized hub and high-performance drive assembly he patented his concept. The best bicycle hubs have up to 6 pawls (which engage in a toothed mechanism) and 36 points of engagement in the drive assembly. Kappius’ design improves on this with 8 pawls and an amazing 240 points of engagement, increasing responsiveness and power to the wheel.
“When I saw it, I got an idea for a new hub-drive system,” said Kappius. “I did a patent search and quickly learned that there wasn’t anything out there that covered what I was thinking.”
His first attempts at manufacturing his design used conventional machining methods which took a lot of work due to the requirement to make frequent changes and improvements in order to stay competitive in the bicycle industry. But in late 2011, Kappius discovered metal laser sintering (DMLS), a form of industrial 3D printing, from German company EOS GmbH.
DMLS printing technology enabled him to produce parts with the required quick turnaround and also with the exacting specifications that his design required. New York based DMLS provider Harbec were used to produce the parts from Kappius’ CAD files. With this process he was able to go from a concept to a completed component in about a month, far faster than than his previous product development cycle.
The Kappius hub benefits from two technologically advanced features; the oversized design and an increased number of points of engagement for the pawls inside the hub which improve the hub’s responsiveness. The oversized housing is made from carbon fibre, making it lightweight, and the internal drive mechanism’s parts are made using DMLS, including the drive ring, toothed inner ring and pawls (or flippers that engage the teeth).
Previous designs used ready-made pawls, but the laser sintered process allows him to redesign them to his own specifications for better performance. More specifically, a one-millimeter cylindrical basal extension allows them to engage better.
“The tool steel is super strong,” he says. “I haven’t had a single hub failure. Even the big manufacturers can’t say that.”
His hubs are now used by riders all over the world and Bicycling magazine included the Kappius hub in a timeline of noteworthy bicycle innovations in their 50th anniversary issue in November 2011.