On a bicycle the left hand pedal screws in one way and the right hand pedal screws in the other way. To anyone that has noticed it the reason is obvious - you don't want the pedals to fall out or work free over time, therefore it is common sense that the threads are different on each side.

However, there was a time before 1900 when you did not have a left-hand thread on one of the two pedals on a bicycle. You probably didn't have bearings in the pedal either and the pedals really could fall out on the one side.

It took the Wright Brothers to see this problem and come up with the solution of using the left-hand thread. Back then there were two patent offices in the U.S., one for bicycles and one for everything else. The Wright Brothers were awarded the patent even though the left hand thread was far from a new innovation, it was the application of that innovation that was what they could patent. This really was a must have feature for bicycles but history has this 'invention' as an interesting footnote to the Wright Brothers story, there are no generally known details as to how they were able to profit from it, which presumably they were able to do to some extent.

There is also another Wright Bros. patent that comes before that. This is for some self-oiling hub. Nowadays bicycle hubs are packed with grease and the last thing you want to do is to oil them. However, once upon a time, oil was what you used to lubricate bearings, and still was the case with 3-speed 'Sturmey Archer' hub gears up until the 1970's. The Wright Brothers innovation was to use some bits of felt as seals, this prevented the oil running out when the bicycle was parked on its side. At that time there were literally hundreds and hundreds of variations on the humble bicycle hub, plus what we know today as a ball bearing had actually only been invented thirty years before hand. No thread sizes were standard so this small bit of engineering was more like home computers before the IBM PC - nothing compatible and all very new.

Much like how the million and one different home computer variants that existed during the 1980's died a death as soon as the IBM PC (and clones) took over, a similar thing happened with bicycles back in the early 1900's. Parts became standardised, bicycles became mass produced and 'craft' manufacturers such as the Wright Bros. could not compete on price. It all happened very quickly, within a short space of time everything ended up being a variant of the Rover Safety Bicycle with Dunlop tyres.

By the time of the 'Patent Wars' the Wright Brothers were quite experienced at applying and getting patents. I suspect that there is a lot more to the Wright Brothers history that needs to be understood, far beyond the potted back-story I mention here. It is also difficult for us to appreciate their inventions, because they are laid out before us. For instance the left-hand thread, the physics going on there are beyond 'well it could work free if the bearings seized', there is this concept of precession that needed some deep knowledge to understand. Similarly with the patent for controlling the plane, the Wright Brothers understood flight at a deeper level and I think they thought there patents should reflect that knowledge and disregard 'workarounds' such as what Curtiss came up with.