Which to buy · Every setting
Fellow Opus vs Rancilio Rocky
Conical against flat — the Opus's scale curves where the other runs straight. The Opus is numbered 1–11; the Rocky is numbered 0–55.
Which to buy
Choose the
Opus if you…
- want 40 mm conical burrs
- want a timed auto-stop at 30, 60, 90 or 120 seconds
- want an inner ring for micro-adjustment between the 41 dial settings
Choose the
Rocky if you…
- want 50 mm flat steel burrs
- grind from a hopper — it holds 0.3 kg
- pair it with a Silvia — Rancilio pitched the Rocky as its partner
Shop links are affiliate links: BrewMark earns a commission if you buy through one, at no extra cost to you. The verdicts were written without regard to it.
Fellow now sells the Opus 2 in place of the original. The settings on this page are for the original Opus. Rancilio no longer lists the Rocky and sells the Stile as its home grinder, so you'd be buying the Rocky used.
Sources: Fellow — Opus (archived) · Fellow — Opus gear guide · Fellow — Opus page today · Rancilio Group — Rocky (archived Jan 2022) · Rancilio Group — Rocky SD specifications (archived May 2022) · Rancilio Group — Stile
| Opus | Rocky | |
|---|---|---|
| Brand | Fellow | Rancilio |
| Scale | Numbered dial | Numbered dial |
| Dial range | 1 – 11 | 0 – 55 |
| Burrs | Conical | Flat |
| Espresso → filter | 5.7 numbers | 20 numbers |
| Filter → coarse | 3.9 numbers | 23 numbers |
The same number means different things
Both grinders use a numbered dial, which makes it tempting to copy a number straight across. Setting 6 sits at grind index 34.2 on the Opus but 1.9 on the Rocky — far enough apart to change the cup.
Converting a setting
If a recipe quotes a setting for one of these grinders, read across for the equivalent on the other. Rows are spaced evenly by grind size, not by dial number — on a conical burr those are not the same thing.
| Opus | Rocky |
|---|---|
| 1.2 | 5 |
| 2 | 14 |
| 3.2 | 18 |
| 5.3 | 22 |
| 7.1 | 26 |
| 8 | 29 |
| 8.2 | 32 |
| 8.3 | 36 |
| 9.1 | 39 |
| 9.3 | 42 |
| 10.2 | 45 |
| 11 | 48 |
| Rocky | Opus |
|---|---|
| 5 | 1.2 |
| 9 | 1.2 |
| 14 | 2 |
| 18 | 3.2 |
| 22 | 5.3 |
| 26 | 7.1 |
| 29 | 8 |
| 32 | 8.2 |
| 36 | 8.3 |
| 39 | 9.1 |
| 42 | 9.3 |
| 45 | 10.2 |
| 48 | 11 |
Side by side, by brew method
Where each grinder lands for the same brew, worked out from its own dial curve.
| Method | Opus | Rocky |
|---|---|---|
| Espresso | 1.2 | 8 |
| Moka pot | 1.3 | 13 |
| AeroPress (short steep) | 3.2 | 18 |
| Pour over — V60 / cone | 6.3 | 24 |
| Siphon | 7.2 | 26 |
| Pour over — flat bottom | 7.3 | 27 |
| Steep and release — Clever / Switch | 8 | 28 |
| Drip / batch brew | 8 | 29 |
| Cupping | 8 | 30 |
| Chemex | 8.2 | 32 |
| French press | 9 | 38 |
| Cold brew | 10 | 44 |
The shape of each dial
Where the connectors bunch, that grinder’s dial is compressed and single steps count for more. Comparing the two shapes tells you which gives finer control, and where.
Fellow Opus
Rancilio Rocky
Dialing in the Opus
Marketed as all-purpose, and it genuinely does cover more range than the Ode, but the espresso end is workable rather than good — expect to chase it. Where it earns its place is the coarse end: cold brew and French press come out notably even. If you bought the Opus mainly for espresso, dial it as a brew grinder first and judge it there.
Dialing in the Rocky
A stepped espresso grinder that has been the budget recommendation for a very long time. The 55 steps across 50mm flat burrs are its limitation — for espresso you will sometimes want a setting between two of them and there is not one, and a single step can move a shot by seconds. Twenty of those steps cover espresso through filter, which is more resolution than the fine end usually gets at this price. Two things make it an espresso grinder in practice rather than a general one: changing setting means holding the locking lever while twisting the hopper, and it keeps a couple of grams in the chute, so every switch between espresso and pour over costs you both fiddling and coffee. Most owners pick one end and stay there.