We may not have made the first gravel bike, but we definitely made the fastest gravel bike. In 2019, spero took the world by storm, heralding a new era of speed in gravel. It was gravel, Cervelo-style. Since then, gravel bikes have grown, fragmented, and started to look a lot like the road and mountain bikes that spawned them, with suspension forks, bolt-ons foreverything, and ever-increasing tire widths.

The new spero remains true to those early, simpler days of gravel, but with some improvementsa threaded BB shell, neater cable routing, and a UDH-compatible derailleur hanger for those who want to use SRAMs Transmission drivetrains. And its faster, of course. We shaved off three watts worth of drag in the redesign process. We also dropped the seat stays to give a bit more compliance out back, and reduced front end stiffness slightly to make the last hours of a long race less painful. Between those dropped seat stays, we added in a bit more clearance for mud, too. Aspero will clear a 45mm tire by ISO standards. ISO mandates a minimum of 4mm of clearance between tire and frame in all dimensions, but weve found (and we think folks at last years unbound will agree) that sometimes you need a bit more than 4mm in muddy conditions. We designed the Aspero around 42mm tires with an additional 3mm of clearance on top of what ISO requires, but if youre feeling lucky (or your rides are typically dry), feel free to push that to 45mm. Its a lot of seemingly small improvements, but they add up to a lot. The result is a bike that feels a lot like the original Aspero, but is faster, more comfortable, and more versatile.

FEATURES:

• T47 Bottom Bracket: spero uses the asymmetrical T47a threaded bottom bracket we pioneered on R5-CX. Its a simple, rider serviceable interface that allows us to deliver the benefits of BBRight in a more user-friendly form.
• Easily Adjustable Front End:spero shares the same bearing dimensions as R5, Soloist, R5-CX, and Caledonia, which means you can use any combination of bearing caps and stems. Want a super-racy, fully internal look? Grab the ST31 and HB13 from R5.
• Universal Derailleur Hanger: SRAM made everyone want to step on their derailleurs when they introduced the Transmission mountain bike drivetrains in 2023. It seems unnecessary, no matter who made your derailleur, but spero uses the Universal Derailleur Hanger (UDH) standard in case you want to try.

SPECS: