When did Shimano quality fall?

[hamster]

You mean when slant parallelogram's patent expired.

Shimano's freehub designs remain a work of genius making bombproof stuff with really excellent sealing. Sadly the pursuit of lightness and oversized aluminium axles has negated that somewhat. Similarly their thumbshifters are indestructible, I'm still using a set I bought in 1990. The modern disc brakes are superb too in value for money and performance.
Against that their chainrings are pathetically soft and my experience is that the chains (while very smooth and silent) have pitifully short lives.

Don't know which Shimano rings you are using or for what style of cycling but my own experience is quite the opposite.
Shimano alloy middle ring used under extreme duress and approx 7k miles and barely worn

Off road. Shimano 32/34T middle rings last around 1500 miles, have even trashed one in 500. TA last 4,000-5,000.

[Tonyf33]

mine is a 36T MTB middle ring, used on road but I'm a 16.5 stone masher and I clean it properly probably once a year with a wipe of the sides now and again.
You must run through lots of crud and never ever bother cleaning it, 1500 miles is all you might expect with poor maintenance

[Brucey]

MTB transmissions, used offroad, wear out about x3 quicker than on the road. Even if you clean the bike every ride, the transmission gets dirty again part-way through the next ride, so it is usually very dirty indeed at least half the time.

Road use normally doesn't compare with that. Not unless you deliberately use grinding paste as a lubricant, anyway.

cheers

[hamster]

mine is a 36T MTB middle ring, used on road but I'm a 16.5 stone masher and I clean it properly probably once a year with a wipe of the sides now and again.
You must run through lots of crud and never ever bother cleaning it, 1500 miles is all you might expect with poor maintenance

I wash my MTB after every ride, then lube the chain correctly. I also use a Park Chain Checker!

Running through lots of crud is the whole point of it.

On my tourer I run a 36T ring and get several thousand miles under a far less diligent cleaning regime - it's all about the conditions