Specialized has launched a radical-looking gravel curious carbon commuter bike

Specialized Sirrus Carbon
(Image credit: Specialized)

Specialized has given its Sirrus commuter bike a radical redesign, the new bike ditches the classic twin triangle frame shape in favor of an interrupted seat tube design which Specialized is calling  'Compliance Junction'. Specialized isn't just a commuter bike though as the Future Shock suspension, space for bigger tires, and a 1X drivetrain means the Sirrus can turn its hand to being a flat-bar gravel bike too.

Built using carbon, the new Sirrus' striking frame design is said to add more compliance to the frame without sacrificing performance. However, rather than use an active suspension system like the recently released Diverge STR, it instead uses a passive system that leverages the flex that can be created through the layup of carbon. 

New Specialized Sirrus Carbon

Removing the lower section of the seatpost is said to reduce vertical stiffness, creating what Specialized calls the 'Compliance Junction' (Image credit: Specialized)

By suspending the seatpost between the dropped seat stay junction and a center triangle stay connected to the downtube, the rear of the frame acts like a leaf spring which is said to offer a more comfortable ride over rough terrain.

The choice to build the Sirrus Carbon 6.0 and Sirrus Carbon X 5.0 from carbon also reduces the overall bike weight too.

To further enhance comfort on and off-road, Specialized has fitted the Sirrus Carbon with their Future Shock suspension design which is also used in their gravel bikes such as the Diverge.

Specialized Sirrus Carbon being ridden through a grassy park

With 42mm of tire clearance the Sirrus Carbon can go off-road too (Image credit: Specialized)

The frame is capable of clearing a 42mm tire for better comfort and grip, or 38mm if you fit fenders. You can also fit racks and there is plenty of bottle cage mounts too with the M, L, XL, and XXL can hold four (two inside the front triangle, one below the downtube, and one on the top tube). XS and S sizes can fit three (one inside the front triangle, one below the downtube, and one on the top tube).

There are two models with slightly different specs available, the Sirrus Carbon 6.0 and Sirrus Carbon X 5.0. The premium Sirrus Carbon 6.0 features a SRAM GX drivetrain, Rival cranks, and Level TLM Brakes. It's fitted with slightly thinner and faster rolling Roubaix Pro 30/32mm tires. The Sirrus Carbon 6.9 is quoted to weigh an impressive 20.3 lbs (9.2kg). The Sirrus Carbon X 5.0 is more affordable and geared a little more towards off-road riding, the SRAM NX Eagle Mechanical drivetrain is fitted with a 38t chainring, rather than a 40t, Tektro TKD-148 brakes, and fatter Pathfinder Pro 38c gravel tires. The Sirrus X 5.0 comes in at 24 lbs (10.8kg).

The Carbon 6.0 will be priced at $3000 / £2400 and the Carbon X 5.0 at $2250 / £1950. Both models come in six sizes, from XS to XXL.

Specialized Sirrus Carbon being ridden through a city street

A lightweight frame should give quick acceleration and agile hangling in town (Image credit: Specialized)
Graham Cottingham
Senior reviews writer, Bike Perfect

Graham is all about riding bikes off-road. With almost 20 years of riding experience, he has dabbled in downhill, enduro, and gravel racing. Not afraid of a challenge, Graham has embraced bikepacking over the last few years and likes nothing more than strapping some bags to his bike and covering big miles to explore Scotland's wildernesses. When he isn’t shredding the gnar in the Tweed Valley, sleeping in bushes, or tinkering with bikes, he is writing tech reviews for Bike Perfect.

Rides: Cotic SolarisMax, Stooge MK4, 24 Bicycles Le Toy 3, Surly Steamroller

Height: 177cm

Weight: 71kg