Specialized is hoping to disrupt the urban landscape with its radically new Sirrus frame design dubbed the “Bicycle Frame with Angled Strut”, which features what the brand refers to as its Compliance Junction technology, wherein the seat tube, down tube and seat stays are triangulated into a boldly executed construction.
“This design advantageously reduce the vertical stiffness of the bicycle while substantially maintaining or reducing to a lesser extent the horizontal (eg lateral and/or torsional) stiffness of the bicycle, thereby increasing the comfort for the rider while substantially maintaining or only slightly reducing the handling of the bicycle and/or force transfer of the rider to the bicycle,” explains Specialized.
According to Specialized, the new design results in 7.9mm of vertical deflection compared to 2.9mm for a conventional frame when a static load of 1,200N is applied, while horizontal deflection at the saddle is increased to 7.2mm compared to 4.1mm for its traditional counterpart.
Additionally, in a horizontal stiffness test where a load of 600N is applied to specific areas of the frame, Specialized says deflection is increased to 5.1mm compared to 6.7mm for a conventional design.
“As reflected in the test results, the [Specialized] main frame produced 172% greater vertical deflection and 75% greater horizontal deflection at the seat during the vertical stiffness test compared to the conventional frame,” says Specialized.
“By increasing the vertical deflection at a greater rate than the horizontal deflection, ride comfort is increased without substantially increasing the rearward saddle tilt.“The horizontal stiffness test showed a decrease of 24% in the horizontal deflection for the main frame compared to the conventional frame which does not substantially impact the ride characteristics (eg handling, force transfer, etc) but it provides evidence that the frame design works well to handle the loads/stresses applied during the horizontal stiffness test, which is believed to correlate to real-world riding,” Specialized adds.
In addition to its Compliance Junction, the Sirrus also features Specialized’s Future Shock suspension head tube technology, which is designed to allow the handlebar and stem to move in order to reduce the amount of high-frequency vibration that’s transferred from the road surface to the rider.
“When the front wheel encounters rough terrain, the bike moves up towards your hands and preserves your forward momentum without slowing you down,” says Specialized. “Because the Future Shock is positioned under the stem, the bike’s wheels are held together rigidly by the frame. In other words, because the wheelbase isn’t changing throughout the suspension’s travel like with traditional systems, you get the added benefit of extremely predictable handling.”
As far as clearance is concerned, Specialized says the Sirrus can accommodate tires up to 42mm without mudguards or 38mm with mudguards.
However, the shortened seat tube means there’s only space for one bottle on the XS and S models, but additional bottles can be added to the down tube and top tube, while M, L, XL, and XXL can hold up to four bottles, two of them inside the front triangle.
The Sirrus is offered in two guises, the 6.0 that sells for $3,000 USD, and the Sirrus X 5.0 for $2,250, which share the same carbon frame and fork, but differ on the drivetrain, brakes and tires, with sizes ranging from XS to XXL.
You can learn more about the new Sirrus and its available options by visiting Specialized’s website here.
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