There was a version where the chain tension was done manually. Unlike the French bike where a cable pulls the tensioner. Here is the lever version with a single cable. You can see the lever tension the chain. This one has the tensioner do the shifting as well. You would loosen the chain and pedal backwards. To actually shift, the rider would literally have to put his hand on the moving chain and push it to the side. You could loose a finger if you were not careful.
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Here is a bike that uses a derailleur built tensioner, but the cogs move while the derailleur.
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The gold bike has an Osgear derailleur, where there is two cables. One moves the derailleur (which is a little slot that pushes the chain) and the other moves the tension arm at the same time. It i quite brilliant.
After the gold bike, Osgear made this derailleur which is basically a 1960s 5 speed derailleur, except with only one jockey wheel.
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Here is a twin pull shifter. The derailleur did not have springs, so a second cable pulled on the end of the derailleur. This was better than a BB mounted tensioner. These were usually made by Cyclo. The top tube shifter would operate the 3 external gears. The handle bar shifter on this bike was made so the bike could have an extra 3 speed hub shifter. These 2 shifters made it a 9 speed bike.
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The 10 speed bike with a 2x10 derailleur was invented around 1948-1949
The first shifting was the Cambio Corsa. This shifter had 2 levers. One to tension the chain and another to shift. These were on the right hand seat stay. The big lever would move the wheel back and fourth while riding, while the small one moved the derailleur side to side.
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The Paris Roubaix shifter, which was later on can do both of these functions with one rod.
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The first multi speed bicycles just had flip flop hubs. This BSA has threads on the left side of the hub for this. These bikes had wing nuts so the rider could flip the wheel with no tools.
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The story is that Tulio Campagnolo was climbing a large hill in Italy, when he needed to flip the wheel to use the larger freewheel. It was so cold that he could not move the wing nuts He did make the climb in the hard gear though. He said "Something needs to change.".