In this series’ previous installment, we covered the wheels-and-tires portion of GRAVELBIKE’s Salsa Vaya 650B conversion. For this entry, we’re going to spend some time talking about gearing.
Salsa has always spec’d the Vaya completes with sensible gearing, and my own Vaya’s gearing (36/46, 11-34) was more than adequate for pavement and gravel. For extended climbs on rocky terrain, however, that gearing simply wasn’t low enough. Drawing on my past experience with 26″-wheeled bikes, I knew that a sub-1:1 low gear would not go unused when exploring more rugged trails.
Achieving that low gear turned out to be a bit of a challenge due to the fact I was running such an eclectic mix of drivetrain components (10s Campagnolo shifters, 9s daVinci/SRAM rear derailleur, Shimano 9s cassette). Taking inspiration from Salsa’s Fargo off-road adventure bikes, I decided that a mountain-double crank would give me the low gear that I needed without having to replace any other components.
To maintain compatibility–and eek out every last bit of shifting performance–many crank manufacturers offer dedicated chainring combinations designed to work specifically with Shimano or SRAM systems. Since my hodgepodge setup contained a mix of both companies’ components, I needed a crankset that would play nicely with a non-dedicated setup. Thankfully, Full Speed Ahead designed their Afterburner double crankset to be compatible with both Shimano and SRAM drivetrains.
Installing the Afterburner crankset was a breeze, requiring only a 5mm hex key and Shimano Hollowtech II-compatible socket. During my testing, I alternated between 24/38 and 22/36 chainring setups, logging the most miles on the 22/36 combo. While it wasn’t designed for such tiny chainrings, the Campagnolo Veloce front derailleur shifted better than expected when it was positioned such that it barely cleared the chainstay.
On paved and gravel roads, the 36t chainring proved surprisingly versatile. There were a few situations where I found myself wishing for a taller top-end, but I never felt handicapped by the 36/11 high gear. When it came to navigating steep, rocky trails, the 22t chainring was invaluable. I could cruise along in the 36t ring, drop down to the 22t when the trail started to get steep, and then fine tune my cadence by shifting up or down the cassette. Thanks to the added height of the 650B knobby tires, pedal strike wasn’t an issue with the 170mm cranks when traversing rock gardens or navigating stair-type obstacles.
If you tend to divide your riding equally between pavement and dirt, consider a mountain-double crankset. For riders seeking a wider gearing range–while still maintaining the simplicity of a double-chainring system–Full Speed Ahead offers the Afterburner in 26/39 and 42/28 combinations.
Disclosure: Full Speed Ahead provided product samples for this article, but offered no other form of compensation for this review.