-
Strange, I was sure hirth linkages on bicycles were licensed by lightening, I wonder if @mdcc_tester can shine any light on the matter?
deleted-
Possibly not true of course. I never checked. The demonstrator guy wasn't a Chicken employee. He thought Shimano was all garbage too. Which its plainly not. Both make nice kit but also both make some rubbish.
-
I was sure hirth linkages on bicycles were licensed by lightening
I'm not aware of any defensible patent on the basic Hirth coupling as it applies to shafts, although there might be some refinements of the surrounding assembly still under protection. AFAIK, the coupling was invented by Albert Hirth, who died in 1935, so the core patent has long since expired. Lightning's patent relates to the integration of the half-axle with the crank arm and in their design the radial alignment and drive torque are handled by dowel pins, not a Hirth coupling. It expired two months ago.
Steve Smilanick had a 1993 patent for using something like a Hirth coupling to join frame tubes for a demountable bicycle, but that too will have expired.
tallsam
gbj_tester
This. Powertorque is my least favourite system. I went to a demo session at Chicken Cycle (distro) and they were saying Citroen own the rights to the Ultra Torque linkage and they have to pay a license fee to use it. Hence Powertorque is their cheapo version.