IMS’s Gaggia-named competition line is B68 — commenters in the r/gaggiaclassic discussion note an outer rim around 68 mm, not the 70 mm B70 / E61 cups. Stock spouted Classic portafilters often reject a B70 ridge or height. Many Gaggia-lug bottomless handles will take a B70. The gram stamp (12/18 vs 16/22) is a range, not a law. Check the exact IMS model code on the retailer’s listing; “58 mm” alone does not identify B682TCH26.5E.
“Which IMS Basket” is a rim question
Read the B68 vs B70 line in the IMS catalogue before choosing a basket labelled “58 mm competition.”
| Common claim | What to check | Source | Key detail |
|---|---|---|---|
| Any IMS 58 mm cup is for Gaggia | B68 is the Gaggia-named rim (~68 mm). B70 is the common 70 mm E61 family | r/gaggiaclassic | Outer diameter |
| B70 never works | Stock spouted PF is fussy. Bottomless Gaggia-lug often runs B70 | r/gaggiaclassic owner discussion | Portafilter |
| 18 g on the box is the dose | 12/18 and 16/22 are ranges; dark roast sits lower | B682TH24.5 / 26.5 owner discussions | Density |
| HBM sells IMS baskets | HomeBaristaMods publishes tutorials and affiliate recommendations. Retailers handle purchases and shipping. | Recommendations and disclosure | Retailer and exact model code |
IMS’s filter guide describes AISI 304 stainless steel and conical holes of 0.25–0.40 mm. Use the model-specific catalogue entry to check B68/B70 dimensions.
Height: 24.5 mm vs 26.5 mm vs taller
On a stock spouted Classic, owners keep repeating 24.5 mm (often sold as 12–18 g) as the cup that still closes, and 26.5 mm (16–22 g) as the usual 18 g home dose if the portafilter allows it. Taller E61 28.5 mm cups are a bottomless conversation. A coin test (puck touching the shower screw) is a headspace check, not an IMS authenticity check.
If you already bought a VST 18 g and it seats, you do not have to “correct” it to B68 unless the spring is unhappy. Ridge vs ridgeless is its own question.
Tamper and IMS
IMS docs and forum users often pair these cups with a 58.4 / 58.5 mm tamper. See 58.5 vs 58.
A precision basket on a 15-bar puck is still an OPV story on older Pros. The basket does not set the spring.
Frequently Asked Questions
What IMS series is for a Gaggia Classic?
B68 is the Gaggia-named rim. Confirm the code, not just “58 mm IMS.”
Will a B70 fit?
Often in a Gaggia-lug bottomless. Stock spouted PF is the risky one.
12/18 g or 16/22 g?
If you dose ~17–18 g, 26.5 mm / 16–22 g is the usual target when the handle allows it. 24.5 mm is the safer stock-PF height.
Is HomeBaristaMods selling IMS B68?
HomeBaristaMods publishes tutorials and affiliate recommendations; we do not sell or ship IMS baskets. Buy from a retailer that lists the exact IMS code you need, such as B682TCH26.5E, and check the retailer’s current price, delivery and return terms.
Do I need a new tamper with IMS?
Usually a 58.5 mm base, not the plastic 58.0 mm stick.
For related guides, visit the Gaggia Classic hub. For group leaks, read when to replace the group gasket.