- IMS CI 200 IM vs IMS SI 200 IM: Effects on espresso pressure, Extraction Yield, puck structure, and radial uniformity
- Reneka micro-sieve vs VST and IMS precision baskets: Hydraulic, extraction and sensory effects in espresso
- Decent small countersunk rinser installation guide
- Evaluating what Michael's spacer and various shower screens do to coffee
- Easy Blooming, compared to the Default and Gentle & Sweet profiles
10g espresso dose: better in a 7g or in a 15g basket?
1. Introduction
In May 2020, Stéphane Ribes documented an experiment asking a practical espresso question: when using a 10 g coffee dose, is it better to use a nominal 7 g single basket or a 15 g double basket? The slides of his presentation can be found here. The reference configuration was a VST 15 g basket, while the alternative was the Decent 7 g basket.
This was not a simple test in which the basket alone was changed and every other parameter held fixed. Instead, the objective was to determine what changes were necessary to make a 10 g dose function sensibly in the geometrically very different 7 g basket. The experiment therefore progressively modified shower-screen geometry, grind size, extraction flow and brew ratio, then compared extraction yield (EY), total dissolved solids (TDS), pressure behavior and qualitative cup characteristics.
The central result is clear: a 10 g dose can produce a pleasant espresso in the 7 g single basket, but it requires substantial retuning and still does not reproduce the extraction performance of the 15 g basket. The final 7 g-basket shot reached only 12.1% EY and 5.5% TDS, versus 20.0% EY and 7.6% TDS in the 15 g reference. The 7g basket also produced less crema and a thinner body.
2. Questions asked
Ribes' presentation addresses five closely related questions:
1. For a 10 g dose, can the 7 g Decent basket produce a shot comparable to the VST 15 g reference basket?
2. What mechanical and extraction-profile changes are required to make the 7 g basket workable?
3. How does the much smaller perforated area of the 7 g basket affect grind requirements and extraction hydraulics?
4. What do a lower extraction flow rate and a shorter brew ratio do to pressure, TDS, extraction yield and taste?
5. Under the tested conditions, which basket is the more suitable choice for a 10 g espresso dose?
These questions reconstruct the experimental logic of the slides from the stated comparison, the tuning sequence and the reported observations.
3. Method
Experimental setup and preparation
The experiment used a Decent Espresso DE1PRO v1.1 fitted with a red Cafelat 8.0 mm silicone gasket. The following two basket/screen combinations were compared, whereby the 7g basket was called single filter basket and the 15g basket double filter basket in the presentation:
The different shower screens were deliberate. Ribes wanted to maintain approximately 4 mm of clearance between the coffee puck and shower screen in both configurations. The CI 200 screen was therefore used with the much shallower 7 g basket.
Grinding was performed with a Mahlkönig EK43 S fitted with SSP “High Uniformity” burrs with Silver Knight coating. Water was Montille water from Le Mont-Dore, France, adjusted with sodium carbonate and Epsom salts to 40 ppm as CaCO₃ alkalinity and 90 ppm as CaCO₃ total hardness.
Portafilters were preheated to 70 °C in a kettle. The basket and shower screen were completely dried before every shot. Beans were single-dosed and ground while frozen into a double-walled stainless-steel cup. For distribution, Ribes used WDT directly in the basket with a Londinium tool and Decent funnel, followed by gentle raking to create a uniform surface. For tamping, he used a Force Tamper with a 58.5 mm smooth flat base at 33 lb, rather than its 24 lb standard force.
TDS was measured with an Atago PAL refractometer, zeroed using the adjusted Montille water. Coffee samples were not filtered, were vigorously stirred and measured at room temperature. Each reported TDS data point was the average of three to five refractometer measurements of the same coffee sample.
Coffee
The package shown on page 6 of the presentation identifies the coffee as OR Coffee Roastery, Brasil – Sitio das Pedras, processed as a fermented natural and roasted as a filter roast.
Important experimental limitation
This is best understood as a tuning comparison, not a strictly controlled one-variable basket experiment. Changing from the 15 g to the 7 g basket also required changes in shower screen, grind, flow profile and eventually brew ratio. Consequently, the experiment shows how the two systems perform when individually adapted, but it cannot attribute every difference exclusively to basket geometry.
4. Proceeding
Establishing the 15 g-basket reference
The 10 g dose in the VST 15 g basket was used as the reference. Its principal settings and results were:
The graph of the reference shot shows a controlled initial flow/preinfusion phase followed by extraction. Pressure builds progressively during the extraction rather than immediately jumping to an extreme value. This became the hydraulic behavior Ribes attempted to approximate with the 7g basket.
Here's the chart of the 15g shot, which he tried to replicate with the 7g basket:
Step 1: adapting the grind to the 7 g basket
The first major problem appeared as soon as the same EK1.1 grind was used in the 7 g basket. Here's the first shots with the 7 g basket, with gradually adjusted grind settings:
The 7 g basket has a much narrower perforated section: approximately 29 mm in diameter compared with 49 mm for the double basket. Ribes estimates that its perforated surface area is therefore approximately 65% lower.
That figure is also geometrically consistent with the indicated diameters:
(29/49)^2≈0.35
so the smaller basket has only about 35% of the perforated area, or roughly 65% less.
The practical consequence was very high hydraulic resistance. In the pressure plots above it's visible that using EK1.1 in the 7 g basket drives pressure rapidly to a very high plateau. Progressively coarsening the grind changes the hydraulic behavior, as visible in the charts above. For easier comparison, the resulting EY are also listed below:
The final required setting was EK2.2, corresponding in the slides to approximately a 90 µm burr gap, compared with approximately 45 µm at EK1.1. In other words, the burr gap had to be approximately doubled.
An important chart-level observation follows from these values: coarsening the grind solved a hydraulic problem, but it did not solve the extraction-yield problem. Across the four 7 g-basket grind settings, EY remained clustered around 12.3–12.6%. It never approached the reference value of 20%.
Ribes interprets the need for such a coarse grind primarily as a consequence of the much smaller perforated area of the single basket. This is presented as a likely explanation rather than demonstrated as a separate causal test.
Step 2: reducing extraction flow
Even at EK2.2, pressure remained undesirable at the higher extraction flow. The next intervention was therefore to reduce extraction flow from 2.7 mL/s to 1.7 mL/s.
The purpose was explicitly hydraulic: reduce extraction pressure and prevent channeling and spraying. The length of the flow ramp was also reduced so that the rate at which water flow increased remained approximately constant.
Below are the charts comparing shots 8, 9 and 10 for reference:
The charts above are particularly informative here. At 2.7 mL/s, the green pressure trace rises very steeply late in the shot and approaches the high end of the plotted pressure range. At 1.7 mL/s, the pressure trajectory becomes substantially lower and smoother, peaking at roughly the 6-bar region rather than approaching roughly 9 bar.
Yet TDS and EY remain exactly the same in the reported measurements: 4.8% and 12.4%.
That means the reduction in flow was valuable primarily for hydraulic stability and pressure control, rather than because it directly increased extraction.
Step 3: shortening the brew ratio
With extraction yield still low, Ribes then changed the output mass instead of trying to force higher extraction from the puck.
Shot 10 (shown above under step 2) retained the 1.7 mL/s flow but stopped at 22 g out from 10 g in, giving a 1:2.2 brew ratio, compared with 26 g / 1:2.6 previously:
This produces one of the most important distinctions in the experiment: concentration and extraction yield are not the same thing.
Using the standard espresso EY relationship as an interpretive check,
Shot 9 gives approximately: 26×0.048/10≈12.5%
while Shot 10 gives: 22×0.055/10≈12.1%
So the shorter shot did not extract more material from the coffee. In fact, EY decreased slightly. What it did was put a similar amount of extracted coffee solids into less beverage, thereby raising concentration from 4.8% to 5.5%.
That increased concentration appears to have helped the sensory result. Ribes describes the final shot as more balanced, brighter and no longer bitter relative to the previous shot.
Visual assessment
In his presentation, Ribes included photographs of the two preparations side by side, apparently documenting the grounds/puck before extraction, the tamped surface, the espresso in the cup, the spent puck and the basket after puck removal.
The cup photographs qualitatively support the explicit observation elsewhere in the deck that the 7 g configuration produced less crema. Ribes also reports a thinner body with the 7 g basket.
The knocked-out 7 g puck also appears less intact around its perimeter than the 15 g puck, although Ribes does not explicitly interpret puck integrity, so this should not be treated as a measured result.
One further documentation gap should be noted: the presentation shows shots 0–4 and then 8–10. Shots 5–7 are not shown, so the complete tuning path between the grind-adjustment phase and the final flow experiments cannot be reconstructed.
5. Results
Final tuned comparison
In his presentation, Ribes reported that adapting the 10 g dose to the 7 g basket required substantial changes relative to the VST 15 g reference: maintaining roughly 4 mm puck-to-screen clearance with an IMS CI 200 shower screen, grinding much coarser from EK1.1 to EK2.2, lowering the extraction flow rate to reduce pressure and limit channeling and spraying, and shortening the flow ramp. Even after these adjustments, extraction performance remained markedly lower: extraction yield fell from 20.0% to 12.1% and TDS from 7.6% to 5.5%. Reducing the brew ratio from 1:2.6 to 1:2.2 partly compensated for the low extraction yield by increasing beverage concentration and produced what Ribes described as a more balanced and quite pleasant shot. However, the 7 g basket still produced less crema and a thinner body than the 15 g reference.
Magnitude of the extraction difference
The final 7 g-basket EY of 12.1% is 7.9 percentage points below the 20.0% reference. In relative terms, it represents only about 60.5% of the reference extraction yield, or a roughly 39.5% reduction.
Similarly, TDS falls from 7.6% to 5.5%, a decline of 2.1 percentage points, or roughly 28% relative to the reference.
The smaller brew ratio partly compensates for the low extraction by concentrating the beverage, but it cannot fully recover the concentration of the double-basket shot. This is exactly what Ribes means by saying that shortening the ratio could “partly offset” the low EY's impact on TDS.
What the charts collectively demonstrate
The sequence of DE1 plots reveals three separate phenomena.
First, basket geometry changes puck hydraulics dramatically. The narrow 29 mm perforated region in the single basket is substantially more restrictive, requiring a grind that would normally be considered extremely coarse relative to the double-basket reference.
Second, hydraulic optimization and extraction optimization are not identical. Moving from EK1.1 to EK2.2 and then from 2.7 to 1.7 mL/s makes the single basket easier to control, lowers pressure and is intended to reduce channeling and sprays, but EY remains at about 12%.
Third, brew ratio can modify cup concentration independently of extraction yield. Shortening the output from 26 to 22 g raises TDS from 4.8 to 5.5%, even though EY falls slightly from 12.4 to 12.1%. This is why the final shot can become more satisfying despite the underlying extraction remaining low.
This distinction is the most useful general lesson contained in the deck: a better-tasting espresso after a recipe adjustment does not necessarily mean that extraction yield has increased.
6. Conclusion
Taken together, the experiment supports the following answers to the questions posed above:
1. For a 10 g dose, can the 7 g Decent basket produce a shot comparable to the VST 15 g reference basket?
2. What mechanical and extraction-profile changes are required to make the 7 g basket workable?
3. How does the much smaller perforated area of the 7 g basket affect grind requirements and extraction hydraulics?
4. What do a lower extraction flow rate and a shorter brew ratio do to pressure, TDS, extraction yield and taste?
5. Under the tested conditions, which basket is the more suitable choice for a 10 g espresso dose?
The broader implication should be kept narrow: this research provides a strong case study of how basket geometry, grind resistance, pressure, flow, extraction yield and beverage concentration interact, but it does not establish a universal rule for every single versus double basket. The evidence applies directly to the specific Decent/VST baskets, coffee, grinder, water and preparation protocol tested here.
mirjam created 2026/08/28, mirjam updated 2026/08/29