Re: benefits/ disadvantages of tensioner-less chain?
On my first bike it was my intention to start with the standard setup: pedal chain adjusted to proper length & tightness - drive chain adjusted with the basic guide wheel/tensioner. This was only until I could get hold of a master link and chain breaker for the pedal chain.
While I had the basic setup, I was not surprised to notice after my first ride that the bracket for the tensioner was doing some creeping. The drive chain does place a lot of leverage on it, after all. So I tightened it down as much as I could, and that helped. But I watched it like a hawk, every time I got on.
Later, I was able to adjust the pedal chain with a master link, so I oriented the whole setup to the drive chain and put the guide wheel/tensioner on the other side with the pedal chain. I was lucky: the drive chain passed by the chain stay on the frame with plenty of clearance.
I am not lucky with my new bike (it's not really new, it's an old Higgins). I tried subtle changes in the way I mounted the engine, but nothing I could do would give the clearance I need between the drive chain and the frame. Under load, that chain would beat the chain stay raw without a guide wheel back there. At least, on the Higgins, the chain stay has a VERY oval-shaped cross section. With the bracket bolts tightened down, that tensioner does not move. At all.
I say, if you can install the engine and drive chain such that the chain does not try to saw through the chain stay - you're golden! That is, in my opinion, the ideal setup. Otherwise, do the best you can. Beware of leverage, don't underestimate it.
"There is nothing wrong with wanting a motorbike that is an extension of your personal taste and fashion sense; if you must ride somewhere, I say do it with style