I agree with most of what you said except for your views on the tensioner. Properly installed and aligned they do not cause problems, do not make noise and do not rob power. The biggest problem with the kit supplied or any chain tensioner is because of improper installation resulting in chain misalignment and several other woes.
Chains wear, so do sprockets and after a period of time there needs to be some method of adjusting for that instead of shortening the chain or moving the rear wheel. Look at any industrial chain drive application and you'll see a method of maintaining proper chain tension, either idler pullys, guides or sprockets, springs or slotted brackets. The reason for them is to keep the chain aligned and tensioned without the need to reposition critical components such as conveyor rollers, platform guides etc. The other function of the tensioner, in the case of our bikes, is to assist in guiding the chain onto the rear sprocket. A loose chain when subjected to side, lateral, forces can sway and that, under the right conditions can cause a chain to derail the rear sprocket with the associated, sometimes disastrous results. Your concern for compromising the integrity of the chainstay by drilling into it is not supported by the successful results of a large number of builders. I have one bike with 1587 miles on the odometer and that's over Colorado streets and roads that are notorious for their rough surfaces. The chainstay was drilled and a 10/32 bolt run through it and the tensioner bracket before the engine was ever fired for the first time. The frame has not failed nor upon inspection of the drilled area is there any evidence of stress cracking or metal fatigue.
As I said, for the most part I totally agree with your observations regarding proper set up and maintenance of a motorized bicycle. Thank you for the in depth information and I'm sure you and I will generate a lot of controversy with our views on the tensioner verses no tensioner opinions. It might be interesting...
Tom

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