Yes that's what happens Dennis and it's why I use a spring tensioner (instead of a fixed tensioner) on the bottom to take up that floppy chain on the return side. The spring type mounted on the bottom (chain stay) solves both issues with one tensioner and the type I use is less than $20. Because there is so little pressure placed on the spring tensioner mounted on the bottom it's practically impossible for the tension device, when adequately tightened, to pivot into the spokes.. So the spring type tensioner also takes care of a real safety issue as well. If the spring tensioner doesn't eliminate excess slack on the return side it's because it's spring is too weak to handle the size chain your using, but if that's the case it's a design issue at the factory. I use the motorcycle style tensioner not the ones made for 415 chain, but even these springs aren't very heavy....just enough. Photo of my hybrid shows two uses of the spring tensioner, both on the return side, the same style tensioner mounted in two different ways. First mounted to the motor housing of the CG to tension the motor chain and on the pedal side mounted to the chain stay. Chain alignment is set by straight line of engine sprocket to wheel sprocket, the tensioner shouldn't be used to correct poor chain line setup by putting side pressure on the chain though it can be used as an idler to control chain sag and side slap. There is a reason that all multi-speed bikes pedal bikes have the derail. spring tensioner mounted on the return side of the chain and it has to control inches of slack chain, perfectly and has done so without changing position for decades, because It works. for that application which is many times more problematic than controlling our little motor bikes inch or two or even three of our little creations. There are many more reasons I can and have given in past posts for using well designed spring type tensioners , but I'll end here with an observation. Some really great engineers figured this problem out many decades ago and it really works well, but home builders really seem to struggle with the reasons why. Rick C.