Hi, this has been bugging & perplexing me for quite a long time now, but this is consistent--so I know there is something to this. Here it is: When I am using newer beans--anywhere from 4 days to about maybe 1 1/2 weeks old--I have to use a coarser grind (4) on my Gaggia MDF grinder. Even with the coarser grind setting, I have to make sure I don't tamp real hard or the espresso will barely drip out.
As the espresso beans get older (after the 1 1/2 week old mark approximately)--I must change the grinder setting to a finer grind(3) or the espresso will pour out fast and lighter. This in turn makes the espresso taste sour and nasty. Too slow & I've got bitterness going on.
As the beans rest longer, get a little older, why does it seem like I need a finer grind, but when they are newer beans, I need a coarser grind?
Am I imagining this? Don't think so. Anyone, Please, pretty please? Thanks!

You're not imagining things. Fresh out of the roaster, beans need a finer grind; but after 4 days, when they've degassed, they are at their coarsest. As the beans age over a few weeks, the grind gets finer and finer.

But ...

Rerdless of age, finer grinds make more laid back shots, coarser grinds make more in your face shots. As the coffee gets older and staler, you are better off grinding coarser and using more and more coffee. When the coffee is very young and powerful tasting, you are better off grinding finer and using less coffee.

When you taste an espresso, ask yourself whether it is too agressive or too laid back. Then grind finer or coarser to correct taste. Once you've set your grinder to get the taste right, set your dose to get the flow right.

another_jim wrote:Rerdless of age, finer grinds make more laid back shots, coarser grinds make more in your face shots. As the coffee gets older and staler, you are better off grinding coarser and using more and more coffee. When the coffee is very young and powerful tasting, you are better off grinding finer and using less coffee.

I don't understand the first sentence. I think you mean "at the same flow rate", which implies a difference in dose. To me, the second and third sentences make a clearer statement of the relationships.

another_jim wrote:When you taste an espresso, ask yourself whether it is too agressive or too laid back. Then grind finer or coarser to correct taste. Once you've set your grinder to get the taste right, set your dose to get the flow right.

I don't see how this can work. When you set the grind finer or coarser, the taste is going to change (presumably to what you want it to be.) But when you add or subtract coffee to get the flow right, the taste will change again.

If you keep flow and brew ratio constant; the grind setting controls the cold taste (i.e. taste parameters derived from extraction). Basket size controls the crema and mouthfeel. My data for this is here. My conclusion is that the grind setting is the primary variable, and that the dose and basket choice are secondary.

My SOP since owning a commercial conical is to taste the coffee, either brewed or as a shot, and set its grind level based on how aggressive or soft I want it to taste. From there, I know what dose each grind setting requires for each basket I own. I'm always surprised that other people who've forked over the big bucks to buy a conical do not know this. To me, the major selling point of commercial conicals is a tight and predictable relation of grind setting to dose for most coffees at most of their age range. This means you can set the grind and know the correct dose for it, with no more BS about humidity, tamp rituals, gremlins, ultra-baskets, or whatever.