The Cartier Ballon Bleu WSBB0030 is the 33mm automatic on a black alligator strap — the version of the Ballon Bleu that skips the bracelet entirely. That makes it one of the most wearable Cartiers in the current catalog, and it also makes the strap more important than on any bracelet model: it is the only part of this watch that wears out, and the only part you can change.
This guide covers the correct strap size for the WSBB0030 and the strap choices that make the most sense for how this watch is actually worn.
Cartier Ballon Bleu WSBB0030 Strap Size and Fit
The essentials:
- Reference: WSBB0030, Ballon Bleu de Cartier, 33 mm steel case
- Correct strap size: 16 mm
On the product page, select the 16 mm option. The Ballon Bleu's case curves in both directions and the lugs sit close to the case, so a strap shaped for this model matters — a generic flat strap leaves a visible gap where the leather meets the curved case. Every Helvetus Ballon Bleu strap ships with its own steel buckle, so it's complete and ready to wear out of the box.
Size by case, not by looks: the Ballon Bleu range runs 28 mm → 14 mm strap, 33 mm → 16 mm, 36 mm → 18 mm, 42 mm → 20 mm, and the sizes are hard to tell apart in photos. The WSBB0030 is the 33. If yours came on a steel bracelet instead of leather, it's a different reference — but the 33 mm size still takes 16 mm, so you can't go wrong within this size.
The Ballon Bleu That Lives on Leather
The Ballon Bleu is named after the blue cabochon-shaped spinel floating in its crown guard — the detail that made the collection famous when it launched in 2007. The WSBB0030 carries the full signature set: silvered guilloché opaline dial, painted Roman numerals, blued-steel sword hands, the fluted crown with its blue spinel, a rounded steel case, and an automatic movement inside. Water resistance is 30 meters, which tells you what this watch is: a dress-leaning everyday piece, not a sports watch — exactly why Cartier sells this reference on leather in the first place.
The Stack Is Hardest on the Strap
Here's the thing nobody tells you about a 33 mm watch: it rarely gets the wrist to itself. This is the size that shares an arm with bangles, chains and bracelets — and in that stack, the most delicate thing isn't the steel case. It's the alligator strap. Metal rubs against it all day, and alligator shows it first: scales scuff, edges lift, and the strap that made the watch look expensive starts making it look tired while the case still looks new.
The answer isn't to stop stacking. It's to give the factory alligator a rest. Wear a smooth leather strap for daily duty — smooth leather shrugs off contact that chews up alligator scales — and bring the factory strap out when the watch goes solo. These are the most popular strap choices among Ballon Bleu owners:
1. Blue Leather – The Color the Watch Is Named After
Look at what's already blue on the WSBB0030: the spinel in the crown, the sword hands sweeping the dial — and the collection's own name. Yet Cartier ships it on black. A blue leather strap for the Cartier Ballon Bleu finally connects those details, and as smooth leather it's built for exactly the daily, bangle-adjacent wear that punishes alligator. One strap, two jobs: it protects the factory strap and it makes the watch make sense. This is the first strap we'd add to this reference.
2. Black Leather – The Everyday Twin of Your Factory Strap
If you love the WSBB0030 exactly as Cartier delivered it, a black leather strap keeps that look on the days that would wear the alligator out. Same color, same restraint, smooth surface that takes the contact — the factory strap stays fresh for the evenings it was made for. This is the low-risk choice, and one of the most popular across the whole Ballon Bleu range.
3. Black Crocodile – The Factory Look, Renewed
When the original alligator does eventually crease and darken — every leather strap does — a black crocodile strap restores the exact register Cartier intended: exotic texture against the guilloché dial, dressed and formal. Keep this one for the days the watch goes on alone, and it will stay beautiful for years.
4. Blue Crocodile – The Dressed-Up Blue
For occasions, a blue crocodile strap combines both ideas in this guide: the color the watch already owns, in the texture the watch was designed around. Croc scales catch light at a different rhythm than the guilloché dial, so the two read as layers rather than competition — the most distinctive way to wear this reference.
You can browse every compatible option in 16 mm in the full Cartier Ballon Bleu strap collection.
One Strap Wears Out. Two Last for Years.
A final point worth knowing: leather lasts dramatically longer with rest days. A single strap worn every day creases fast because it never fully dries and recovers; two straps in rotation each last more than twice as long. On a watch with no bracelet in the box, a second strap isn't an accessory — it's how you keep the watch looking the way it did the day you got it.
Final Thoughts
The WSBB0030 hands you one decision, and it's a good one: the strap is the whole personality of this watch. Helvetus is one of the leading names in the aftermarket strap world, and our Ballon Bleu straps are shaped for the curved 33 mm case — an exact 16 mm fit, complete with buckle. Rubber straps across our range carry a lifetime warranty, shipping is free worldwide with no import costs, and more than 50,000 watch owners already trust us with their straps.
Cartier gave this watch its dial, its crown and its curves. The strap is yours.
