in this case it was inscrutable Japanese motorcycle engineers who decided to put a muffler right next to the axle nut which you need to loosen to adjust the chain tension. I could remove the muffler but that adds a whole 'nuther level of PITA to what should be routine maintenance.
And of course it's a 19mm nut and my current set of metric wrenches only goes up to 18mm. I might try to find a single 19mm box end wrench, the longer the better and just TFAR it. What's the standard torque equivalent for "farmer tight"?
But seriously, I'll go ahead and get the right tools and then I'll have them. Thanks to all for the info, this helped a lot.
