Earlier this year Specialized released a patent for a new frame design which incorporated a ‘strut brace’ and saw the removal of a lower section of the frame’s seat tube. The radical design, said Specialized, resulted in improved comfort with no compromise in ride quality.
We weren’t sure that this new design would make it to market but did speculate that if it did it’d be on a gravel or endurance bike, potentially adding itself to the pantheon of revolutionary road racing bikes. We were wrong on both counts, as this highly distinctive frame is here and it’s in the shape of the all-new Sirrus Carbon – the update of the brand’s flat bar fitness and commuting favourite.
The Sirrus Carbon is offered in two models, the 6.0 and the 5.0 X, with both frames constructed using the brand’s FACT 9r carbon layup. Still aimed at the leisure market, where the best hybrid bikes reign supreme, the revamped frameset cuts a distinctive silhouette, thanks to what Specialized are now calling the ‘compliance junction’.
(Image credit: Specialized)
Rather than the seat tube meeting the bottom bracket, it instead ends abruptly around the mid-wheel point, joining with the super low seat stays, which then continue on to the down tube. The result is striking; the design essentially leaves a hole where the rest of the seat tube would typically be.
If the response to Trek’s latest Madone, which also features a ‘hole’ in the frame, is anything to go, expect this latest Sirrus Carbon to make plenty of headlines, and likely a few waves, too.
As the compliance junction name suggests, the ‘look’ is created in the name of comfort. Specialized says the design creates “just the right amount of flex across the carbon frame without sacrificing performance and efficiency”.
When the patent was released, Specialized was quoted as saying that tests of of the new frame “produced 172% greater vertical deflection and 75% greater horizontal deflection at the seat during the vertical stiffness test compared to the conventional frame, and that “The horizontal stiffness test showed a decrease of 24% in the horizontal deflection for the main frame.”
(Image credit: Specialized )
But the pursuit of forgiveness isn’t all radical. The new Sirrus is also equipped with FutureShock 1.5, the same front end suspension system that is featured on the Roubaix road bike and the Diverge gravel machine, as well as some previous Sirrus models. Positioned inside the headtube and delivering 20mm of…