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Tudor Black Bay Chrono 39 "Bumblebee": A Smaller Chrono with a Lot to Say

Tudor finally gets the Black Bay Chrono down to 39mm, and the first version out of the gate wears a yellow-and-black "Bumblebee" dial. Here's what changes, what it costs, and why the size matters more than the colour.

By the WristBuzz team Published June 5, 2026 5 min read
Tudor Black Bay Chrono 39 Bumblebee reference 79310N with yellow dial and black sub-counters
The Tudor Black Bay Chrono 39 "Bumblebee" (Ref. 79310N). Yellow dial, black sub-counters, 39mm steel case. Source: SJX Watches.

Tudor has been making us wait. The original Black Bay Chrono landed in 2017 at a chunky 41mm, with a movement co-developed with Breitling, and a wear that never quite matched the Black Bay diver it shared a name with. Eight years later, that wait is over. Meet the Black Bay Chrono 39 "Bumblebee" (Ref. 79310N): a 39mm case, a fully in-house COSC-certified chronograph movement, and a yellow-and-black dial that does not pretend to be subtle.

The 4mm size drop is the news. The colour is the hook.

What actually changed

The new case is 39mm wide and 13.1mm thick. Lug-to-lug shrinks proportionally. That matters because the old 41mm chrono wore like a 43mm thanks to the curve of the lugs and the height of the sapphire. The 39 will sit on a wider range of wrists, full stop. Tudor finally made the chronograph their own divers always could have been.

Inside is the in-house Manufacture Chronograph Calibre MT5813. Column-wheel architecture, vertical clutch, silicon balance spring, 70-hour power reserve, and COSC certification out of the box. This is the same movement family that powers the bigger Black Bay Chrono, slotted into the smaller case without losing the power reserve or the chronometer rating.

The size point
Tudor has spent a decade arguing that a Black Bay should fit a 6.5-inch wrist. The diver got there in 2022 with the 39. The chrono just caught up. If you have ever tried a 41mm Black Bay Chrono and put it back, this is the version you were waiting for.

About the dial

Close-up of the yellow Bumblebee dial of the Tudor Black Bay Chrono 39 with black sub-counters and date window
The yellow dial pairs with black sub-counters at 3 and 9, plus a date window at 6. Source: Fratello Watches.

The "Bumblebee" name comes from the colourway. A bright yellow base dial, two black sub-counters at 3 and 9 o'clock, and a black tachymeter scale around the perimeter. The hands are luminous, the indices match. It is not the first time Tudor has put yellow into a sport watch (see Pelagos FXD Alinghi yellow accents), but it is the first time it has committed an entire dial to it on a chronograph.

The yellow is louder than anything Tudor has done on a Black Bay. That is, you suspect, the point. The watch is part of Tudor's Daring Watches collection, which signals limited production and colour-forward design rather than the heritage palette of the standard Black Bay range.

The specs at a glance

Reference
79310N
"Bumblebee" Black Bay Chrono 39, steel case, yellow dial.
Case
39mm × 13.1mm
Stainless steel, screw-down crown, sapphire crystal, 200m water resistance.
Movement
Calibre MT5813
In-house, COSC certified, column-wheel, vertical clutch, 70h power reserve, silicon balance spring.
Price
€6,200 / $6,725
CHF 6,000. Available now as part of the Daring Watches collection.

Where this lands in the line

The Black Bay Chrono 39 slots in below the 41mm S&G two-tone, well above the basic Black Bay 41, and in a price band where the alternative is a Speedmaster Reduced (no, do not buy a Speedy Reduced) or a Breitling Top Time. Against those, Tudor brings COSC, an in-house movement, a 70-hour power reserve, and a 200m water resistance number that none of them match. Add the smaller case and the dial colour, and Tudor has stopped competing on price and started competing on character.

Some quick collector notes:

Is it the chrono to buy?

For the buyer who has been holding off on a Black Bay Chrono because of the size, yes. Categorically yes. The MT5813 is one of the best automatic chronograph movements at the price, the new case finally proportions correctly, and the dial is a real conversation piece.

For the buyer who wants a quiet daily-driver chronograph, look elsewhere in the line. The Bumblebee is the loud one. It is meant to be. Tudor has made the chronograph it always could have, and then put it in the most attention-getting dress it owns.

If yellow is not your colour, this matters less. The point of the 79310N is that the 39mm case exists. It almost certainly will not stay limited to this dial.

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