I have been riding for over a year without a drive chain idler, and never had a problem like that. I dont know if anyone else has ever had that problem, but I haven't.From my experience, a spring-loaded tensioner on chains is just about necessary for long-term daily riding.
Without a true tensioner, the chain can be subject to misalignment at any time - especially when hitting a bump while leaning during throttle changes.
I've also put on about 1.7K miles without a chain tensioner and haven't had that problem, or any problem for that matter. I'm running a #41 chain without a master link (and no half links), so far my chain hasn't loosened up on me at all. I tend to ride kinda hard, and weigh over 200lbs, although I only ride on the street for the most part.I have been riding for over a year without a drive chain idler, and never had a problem like that. I dont know if anyone else has ever had that problem, but I haven't.
The #41 industrial/farm chain I am using said it was "pre-stretched", so it should be at it's final length before it's installed on the bike, which has been my experience...After an initial stretch it should take a set at a length and stay that way, if not the chain is cheapo.
New chains DO go through an initial stretch, that is why quality industrial chains are "pre-stretched" to eliminate that initial stretch. These china kit chains, however, are not pre-stretched, and are made from such poor material the initial stretch and wear can be pretty serious.Roller chains don't 'stretch'...they wear.
That is my point, the chain that comes with these kits from china (that I have received) are so poor that you should do yourself a favor and throw it away and get a real chain. They do "stretch" when initially stressed because they have not been pre-stressed and are poorly manufactured with low quality materials. I had links elongate and snap, at least a bungee snaps back! LOLIf a chain did ever actually "stretch" I'd throw it away immediately & wonder what they were thinkin' when they started makin' them outa bungees...
Chain stretch, chain wear *shrug* the only difference is clarity really.