I do understand the derailleur principle. That was an excellent explanation though.
Part of my reasoning agrees with your explanation. Pushing forward on the lever relieves the tension, not only on the cable but on the lever as well allowing the lever to move forward. So in effect it would also act as a way to get the lever out of the way.
In that situation the movement of the derailleur is not as important as the movement of the rider and the shift lever.
About the Consumer Product Safety Commission.
That fiasco started with Ralph Nader and his Unsafe At Any Speed rant. For thousands of years boys have played dangerous games, done dangerous stunts and altogether lived dangerous lives.
Do you remember a game called Mumbltypeg? Throwing a pocket knife to see how close you can get it to the other players foot is probably not as safe as playing World of Warfare, but it got kids out of the house and in the fresh air doing something. We played Army, sometimes with BB guns climbing on and jumping off garage roofs and out of trees. Yet somehow I lived thru all that without any help from the CPSC.
I owned and built stick shift bikes when they were still new, and I rode them like I stole them. I once jumped a six foot dirt mound at full speed in fifth gear. Everything was cool until I flipped over and landed about 30 feet from the hill, right at the edge of the street with the bike on top of me. I got up bleeding from the scrapes on my arms and back. Not counting the nose bleed from the bike landing on me. My bike was fine, it had something soft to land on. So I rode it around the block, back to the construction site and jumped the hill again. That time I landed the way I was supposed to. Boys all over America were probably doing the same thing and some of them were getting hurt.. What was the CPSC going to do about that? Outlaw dirt hills? Or bicycles altogether?
We live in a nanny state and it all started with the CPSC. The day the Stik Shift disappeared from bicycles was the day the Stingray and a lot of other bikes died. But it didn't stop boys from doing dangerous things. Skateboarding and BMX were no more safe than what I did on my Stik Shift Stingray.
That was almost 50 years ago. By now the CPSC has outlawed everything that they could possibly perceive as dangerous.
Some places you cannot buy spray paint or model cement unless you are 18 or older. When I was 14 I probably bought a can or more of spray paint a day to fix up an old bike I picked up off the curb. Imagine what a pain in the @$$ it would've been to get my parents to go to KMart or Sears and buy me spray paint every day. We only had one car and my dad worked 2 jobs. The only time my mom had the car was a couple hours in the mid morning, he would get home around 8:30-9:00am and have to be at the other job by 2:00pm. I was in school that whole time so I would've been out of luck if the CPSC would've accomplished what they have done now 50 years ago. I hate the CPSC and everything they stand for. It isn't about safety. It is about power and control.
I could rant on this for hours, but I have other more fun things to do. It is hard to clean bike parts when you are typing on a forum. I do not know your age man, but I am 62 years old. The clock is ticking for me and I do not know how many times I am going to get to wind it up again before it quits working.
Hey man, like I said earlier your explanation of how a derailleur works was excellent and I could not have done better. Maybe my belief that it also helps the shifter move forward in an accident situation is a secondary benefit but the benefit is still there. I am fairly certain they only use that overload tube on some Stick Shifters, Schwinn and Shimano are the ones I know of from my era. There are no overload tubes on any other type of shifter, so there must be other ways to accomplish the function that the overload tube does. Why didn't they use one of those methods?
I appreciate the work you did to type out that explanation, as I am sure others also do. The debate was cool for me and I hope it was for you as well man.
Thanks, Rob