Dosing on Gaggia Classic

Beginner and pro baristas share tips and tricks for making espresso.
coffeeguyCT

#1: Post by coffeeguyCT »

Hi all

I just rebuilt my old Classic and got a new Breville Smart Grinder to replace a very old one. Taking this occasion to add some more precision to how I make espresso. I read this article that talks about a 1.5-2.5 brew ratio. What I don't know is the intended capacity of the double basket that comes with the classic. The article says 18-21g is a good guess absent a stamping on the basket (which it does not have). Any other intel?

https://prima-coffee.com/learn/article/ ... esso/31702

jrham12

#2: Post by jrham12 »

When I had a Gaggia Classic (the "PRO" model from 2019), I found that about 16.5 to 17 grams was my max dose in the stock double basket... Any more than that and I think I was not leaving enough headspace which probably contributed to a lot of channeling issues I was having.

I'd highly recommend performing the "nickel test" to see what your max is. Put your normal dose (say 17 grams) in the basket and tamp as usual. Then lay a nickel on top of the puck before inserting it into the machine. Insert the portafilter and tighten it in as usual. Then take it back out and look to see if the nickel has left an imprint in the puck. If it has, then the dose is a bit too high to leave enough headspace between the puck and shower screen. If 17 gr is too much then try it with 16.5. If you do not see an imprint, then go higher to see where the limit is.

But keep in mind that as you change grind size (and beans) the value may vary a bit.

Hope that helps!
Josh

DamianWarS

#3: Post by DamianWarS »

coffeeguyCT wrote:Hi all

I just rebuilt my old Classic and got a new Breville Smart Grinder to replace a very old one. Taking this occasion to add some more precision to how I make espresso. I read this article that talks about a 1.5-2.5 brew ratio. What I don't know is the intended capacity of the double basket that comes with the classic. The article says 18-21g is a good guess absent a stamping on the basket (which it does not have). Any other intel?

https://prima-coffee.com/learn/article/ ... esso/31702
I think the Gaggia Classic's stock basket is closer to a 14-16g dose. @jrham12 however is right and you can find the max limit of your basket using the nickel test. he seems to have hit a 17g dose which is an odd size dose and is unlikely what the basket was designed for specifically but the result would be accurate even if the basket is not marketed that way.

the Gaggia classic I think is getting its reference from traditional Italian espresso which is more commonly 7-8g. if we see that as a single shot then 14-16g is a double. this is also why you will see a 21gr rated basket which is an odd size number too but it is divisible by 7, which makes it a triple shot. This original single-shot frame of reference is somewhat arbitrary today but these are the reasons why you see some odd numbers like 21 marketed but not others like 17 or 15 (or at least rarely). a broad range for a double probably is more 14, 16 (all even numbers from their frame reference being 2x the single shots, 7 and 8 After that, you will see some more odd numbers like 21 and again you see this more often because the frame of reference is triple of a single. 24 would be a triple from the frame of reference of an 8g single and 18 can be a triple of 6gr (a lower end of a traditional single shot) or a double of 9 (a higher end of a traditional shot). with laser precision baskets like VST they can have any size (I think they carry 15, 18, 20, 22, 25). broadly speaking with these baskets you can plus/minus 1gr so the 15 is similar to saying 14-16. and the 18 is 17-19, and looking at it from this perspective their sizes makes more sense as they cover a full spectrum of 14-26gr with more overlap in the low 20s as those sizes probably have more demand.

with regards to headspace, You can do the nickel test which is pretty quick and simple or if the shower screen is always dirty with coffee this will probably indicate you're overfilling your basket. every coffee is slightly different and may expand differently or be of a different hardness so you may find with ABC coffee you can get away with 17gr but XYZ 17gr is too much. if the shower screen is always dirty this might prompt you to do the nickel test which then may determine you should dose down. As you use the machine you get a better sense for when is too full. I don't do nickle tests because consistently dirty shower screens are a good enough indicator for me to dose down

coffeeguyCT (original poster)

#4: Post by coffeeguyCT (original poster) »

Super helpful thanks. A few possibly dumb q's -

Should I not be rotating the filter CCW past the triangle symbol (first pic) to tighten it as much as possible (second pic) ? This will obviously effect the nickle test.




Confirming the capacity of the 2-shot basket effectively limits the max shot you can pull (without running past advisable ratios of grounds to shot mass)

smithflys23

#5: Post by smithflys23 replying to coffeeguyCT »

If your portafilter rotates that far, it may be time for a new group gasket.

coffeeguyCT (original poster)

#6: Post by coffeeguyCT (original poster) »

It has a brand new one. It's the cafelat silicone (blue) one. https://www.amazon.com/gp/product/B07KV ... UTF8&psc=1

Quirquincho

#7: Post by Quirquincho »

My new cafelat silicone gasket also lets my pf rotate that far, but mine is the yellow/orange-looking one. The previous one I had, which was the same cafelat one, was a bit tighter. I don't know why the difference, but it seals properly, so not worried about it.