Bigger wheels and more travel for the Calibre Bossnut
Affordable alloy trail bikes. Since its launch in 2015, Calibre’s Bossnut has been a viable pathway into the confidence of a dual-suspension trail bike for riders on a budget. After nearly a decade in the market, Calibre has significantly updated the Bossnut, adding more travel, bigger wheels and progressive geometry.
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The most significant change with the 2025 model year Bossnut is wheel size. After seasons of 27.5-inch wheels, the new range transitions to 29-inch, but for the XS size, targeting pre-growth spurt teens and compact riders.
Bolder geometry
Calibre’s decision to upgrade the Bossnut range to 29-inch should aid obstacle rollover, cornering and braking traction. The product development team considered a 29/27.5-inch mullet configuration but opted for the balance of an all-round 29er set-up.
With the move to bigger wheels, the Bossnut has gained more suspension travel, too. Fork stroke increases from 130- to 140mm, and frame travel grows by 5mm to 135mm. The suspension is by RockShox, with a Recon RL specification fork and Deluxe Select shock.
True to its role as a trail bike, the 2025 model year Bossnut geometry features a much slacker head angle, low bottom bracket height and generous reach. Cockpit geometry should provide a lot of steering leverage, with a 780mm width handlebar clamped into place by a 45mm stem.
With a 64.5-degree head angle, the new Bossnut should stay balanced on even the steepest trails, while the 78-degree seat angle should conversely keep riders in a powerful position, when spinning up severe gradient climbs. On a size L, reach measures 475mm, 15mm more than its predecessor.
A peculiarity of previous Bossnuts, was that they shipped without factory-fitted dropper seat posts – an almost unimaginable components choice for a contemporary trail bike. Calibre has addressed this with the new range, including size-specific droppers for all sizes, 125mm droppers on the XS/S frames, 150mm for M, and 170mm on the L and XL sizes.
The gears you need
To keep the new Bossnut’s pricing aligned with its affordability legacy, Calibre has chosen a 1x10 drivetrain. And yes, that’s two gears less than you’d expect from most new mountain bikes. Still, unless you’re a cross-country racer obsessing about tiny steps between ratios and overall efficiency, the 1x10 drivetrain can be entirely adequate for most terrain profiles.
For most riders, the 11-48T cassette and 32T chainring should have adequate gearing spread for most trail-grade climbs. Durability should be excellent, too, with a traditional 73mm threaded bottom bracket and Shimano’s Cues drivetrain components, which add a touch more material and weight to enhance the cassette and chairing lifecycle.
Brakes are also by Shimano, with MT401 specification levers and calipers, acting on 180mm rotors. Those rotors are mounted on alloy wheels, rolling 30mm internal diameter rims laced to Shimano TC-500 hubs. With 32-spokes front and rear, these wheels should withstand most impacts you’re likely to encounter boosting small jumps and rolling off mild drops.
Tyres are a crucial confidence component on any trail bike build and the new Bossnut rolls a 2.5in width Maxxis Minion DHF up front, and 2.4in Forekaster at the rear. Both tyres are the Maxxis EXO casing, although it's notable that the Minion DHF specification chosen for the new Bossnut has a wire bead.
As expected from Calibre, the Bossnut is competitively priced, positioned at £1,499 and available from GO Outdoor.
www.gooutdoors.co.uk