Strap for Speedmaster 57 Co-Axial Titanium / White / Bracelet

The lug width of the Speedmaster '57 331.90.42.51.04.001 is 20mm. This measurement is proportionate to the case diameter of 41.50mm and represents a standard derived from the historical proportions of the 1957 model. When replacing the original strap with an aftermarket option, it is essential to verify that the lugs are exactly 20mm wide, as even minimal differences (±0.3mm) would cause play or binding during installation.

For the Speedmaster '57 in titanium, we recommend straps in alligator leather with vegetable tanning or structured calf leather with regular grain. Alligator imparts formal elegance without adding weight to the titanium case, while fine-grained calf enhances the watch's sober geometry. Avoid straps that are overly padded or feature deep grooves, as these would contradict the instrumental essence of the design. Titanium requires an aesthetic partner that does not conflict with its constructive austerity.

Strap replacement requires the use of a spring bar tool or dedicated implement to release the internal locking spring. Position the watch on a stable surface, locate the small lateral slots beneath the lugs, insert the tool into the slot and apply gentle pressure to compress the spring. Once one spring bar is released, repeat the procedure on the other side. Install the new strap by aligning the lugs with the case seats and verify that the spring bars are fully locked. If you prefer professional service, the Casati Milano atelier can perform the change with certified precision.

Yes, aftermarket straps with 20mm lug width are fully compatible with the Speedmaster '57, provided they are certified for this lug measurement. On milanostraps.it you will find a collection of artisanal 20mm straps in natural leather, alligator, shell cordovan and NATO fabric, all available for rapid shipment. If you desire a custom strap with exact measurements, embroidered initials or personal leather choice, Casati Milano creates bespoke straps in-house with an 18-month warranty.

The lifespan of a leather strap depends on the tanning method and frequency of wear. An alligator strap with vegetable tanning, if worn 5-6 days per week, maintains structural integrity and flexibility for 4-6 years before requiring replacement. Structured calf tends toward a slightly shorter lifespan (3-5 years) due to constant wrist pressure. Shell cordovan is more durable and can exceed 7-8 years. To extend lifespan, alternate use with backup straps and clean the strap monthly with a soft brush and tepid water. Casati Milano provides an 18-month warranty on all in-house manufactured straps.