Strap Check: Does The Omega Speedmaster Chronoscope Clasp Fit The Regular Moonwatch?

It’s safe to say the new 3861-equipped Omega Speedmaster Moonwatch caused a big splash at Fratello. Since the launch in January 2021, at least four team members obtained Omega’s first Master Chronometer Moonwatch. All smiles, then? Well, overall, yes. The Speedmaster is one of my most prized possessions, and not just in terms of watch collecting. Every time I wear it, I can’t help but spend some “me time” ogling its many intricacies. However, on the wrist, a niggling feature, or lack thereof, began permeating my psyche and spoiling the wearing experience. In this somewhat different Strap Check article, I aim to tackle my reservations about the bracelet and remedy them with a solution. Does it work? Read on to find out.

As far as opinions go, it was pretty clear that the outgoing 2020 Speedmaster bracelet was not to everyone’s taste. Replacing the reference 1479 in 1996, the 1499 bracelet saw gentle iterations over its nearly 25-year reign. The changes include screw links replacing pins and collars, as well as studier machining techniques. While later variations had a subtle taper from the 20mm end links to 18mm, the clasp still felt clunky and disproportionate to the case. In 2019, the Moonshine Apollo XI demonstrated alternative metal options to complement the Speedmaster case. Even though the bracelet references the Speedmaster ref. BA145.022-69 design from 1969, the style was fresh and exciting. The fit and finish set the bar against its vintage counterpart and the contemporary Moonwatch. So much so, in fact, that in 2021, a similar bracelet design became the de facto pairing for the stainless steel Moonwatch.

Two generations of Moonwatch models (Left: new, right: previous)

Link to a new era

The new bracelet flows from the Speedy case with far more fluidity. The aesthetic appears more refined with female end links and a dramatic taper from 20mm to 15mm at the clasp. The hulking mass of steel that was the outgoing Moonwatch bracelet seems ungainly in comparison. While it still has a subset of fans, I think we can agree the new bracelet has a reduced visual weight. Not long after praising the current construction, nay-sayers pointed out the omission of an easy-adjust clasp. Easy-adjust or comfort extension refers to a button or slider that allows a degree of bracelet length adaptability without using tools. Sure, there are dual pinholes on either side of the new Moonwatch clasp. A pin, spring bar tool, or even a cocktail stick can extend or shorten the bracelet by shifting the connection closer to the edge or further into the clasp.

But when using the outer clasp holes, I find the step down of the T-shape link disrupts the flow of the bracelet. Besides that, on-the-fly adjustments exist to give your wrist some breathing space on a whim. My wrist was swelling recently on a plane journey, even though my heart rate was regular and I was reasonably cool. Bringing a sharp spring bar tool may raise the alarm and divert the trip to the nearest airport. Not only that, fumbling with spring bars in a tight airline seat is fraught with danger. Even the most careful approach could send a spring airborne through the cabin. But the discomfort I began feeling was unbearable. I took the Speedmaster off a few times but couldn’t exactly sleep soundly, knowing a fellow passenger could make off with my watch. On-the-fly (pun intended) adjustment would’ve been ideal in this scenario.

Chronoscope clasp — PUSH to slide

It’s not like push sliders are a new concept at Omega. The Planet Ocean and Seamaster Diver 300M have many diving-extension capabilities. The omission on the latest Moonwatch was compounded when in September of the same year, Omega launched the Speedmaster Chronoscope. The offshoot Speedmaster with a historic model name has a dazzling array of timing scales. But don’t let the dial or new caliber distract you from a hidden detail. Within the Chronoscope clasp is the coveted “PUSH” button that Moonwatch wearers, myself included, longed for. Not everyone agrees about the extension button, as RJ explains in his Moonwatch “year on the wrist” article here:

“It would have been nice to have an easy adjustment system, but perhaps the clasp would become too bulky. I don’t know. Either way, I rarely resize my bracelets, but I know some of you that have been waiting for a proper adjustment mechanism will just have to keep on waiting.”

The design of the Chronoscope bracelet is remarkably similar to that of the Moonwatch. And seeing the mechanism implemented flawlessly in a similarly sized clasp had me yearning to experiment. After a quick stop at my local authorized dealer, my order was in place for the separate Chronoscope clasp. For clarity, the part reference is 117STZ013899, and I paid £162.62 — this price may vary in your local currency. I was surprised to see how closely it resembled the Moonwatch clasp when it arrived. The grooves on the outer side and the logo that teeters over the edge are precisely the same. While we reported that Chronoscope clasp is 16mm wide, this clasp is 15mm, the same as that of the Moonwatch.

Get ready for numbers

The wheels were now set in motion, with the initial measurements looking good to swap the clasps — until I hit a substantial roadblock. While the bracelets appear similar, the Chronoscope clasp’s central connecting arm is slightly wider by 2mm. The 7mm central connecting bar is too wide to fit in the 5mm gap in the Moonwatch links. Therefore, the Chronoscope clasp as it comes out of the box will not attach to the Moonwatch. Luckily, the entire folding arm element is removable via a spring bar on both versions, which also share the same 12.5mm internal gap. By swapping this part, I was indeed able to affix both sides of the bracelet to the clasp. Now, the push of a button lets me extend the links by 2.3mm (half a link) when on the move without tools. The Chronoscope clasp also doesn’t have pinholes on the sides, so it cleans up the overall design.

Streamlining the look was not the primary goal, but it is a surprising benefit. The 4mm shroud over the extension side hides the T-shape link even when fully extended. With this shroud, the clasp is longer at 33mm versus 29mm, but it allows for continuous lines from bracelet to clasp. But as comfort was the main attraction for buying the clasp, how does it stack up? RJ believes that a bracelet is set for good once he sizes it. But with my Moonwatch, I often found it too tight by removing one link and too loose when I put it back in. Even with relatively small links, the variance was frustrating. The outer pinholes were an option, but I was not too fond of the unsightly T-shape link that broke the flow between the components. The Chronoscope clasp solved both issues by adjusting on the fly for any wrist variance and hiding the mechanism.

Final thoughts on the Chronoscope clasp

It’s not a perfect solution, however. When the clasp is closed, the folding arm of the Chronoscope is designed to fit flush on either side of the “PUSH” button. The Moonwatch’s broader outer folding arm components sit on top of the button instead of neatly slotting on either side. It’s no problem for closing and securing the clasp, but it raises it slightly by 2mm on the bottom of the wrist. From the package I received, it appears I’m missing a link that would connect the Chronoscope arm to the existing Moonwatch bracelet. But as this did not arrive as part of the order, I am seeking to order this separately. The reference for this component is 118STZ013110. I can’t see this damaging the PUSH mechanism, but I couldn’t give my 100% endorsement to fitting the Chronoscope clasp to the Moonwatch until I have tested this part. But RJ has already alluded that an official upgrade with the PUSH button may be coming to the Moonwatch soon:

“…Omega will also come up with an upgraded clasp like this for the regular steel Speedmaster Professional watch. Current owners of that watch will be able to replace theirs as well with the new clasp. But all in due time — Omega could not give us a timeline for this upgrade.”

We’ll see if this comes to fruition, but there are promising signs considering the new Moonshine gold with green dial/green bezel and golden panda models both implemented the comfort-adjust feature. This is a good option for current Speedmaster Moonwatch owners that want a little toolless adaptability throughout the day. As mentioned, the clasp component reference is 117STZ013899, and the price is £162.62.