The name Bossnut needs no introduction in the mountain bike world. Originally launching almost a decade ago, the Calibre Bossnut redefined what an entry-level full-suspension bike could be, earning a reputation as our MTB of the Year. Now the 2025 Calibre Bossnut Pro takes things up a notch. Built to perform in almost any conditions, it’s become a legend for its ride quality, handling and unbeatable value.

Built on the same award-winning frame but with a tougher custom tubeset, improved cable routing and added bosses for tool storage, the Bossnut Pro is stronger, tougher, and ready for years of riding. Choice component upgrades make it the bike the Calibre team riders wanted, including a RockShox Psylo Gold fork, RockShox Deluxe Select+ rear shock, Shimano 4-pot hydraulic brakes, a 12-speed Shimano Deore drivetrain and Maxxis tubeless-ready tyres. With Boost hub spacing for extra stiffness and space for a bottle cage inside the frame, the Bossnut Pro is the complete package for riders moving up from a hardtail or chasing their next trail challenge.

Size info

XS - 5'5" (165cm) to 5'9" (175cm)

S - 5'6" (168cm) to 5'10" (178cm)

M - 5'8" (173cm) to 6' (183cm)

L - 5'10" (178cm) to 6'2" (188cm)

XL - 6'1" (185cm) to 6'6" (198cm)

Spec details

• Frame: 29” 6061 Alu, boost spacing, 135mm rear travel, 73mm BSA BB
• Thru-axle: M12, pitch 1.5, length 174mm, thread length 20mm
• Forks: RockShox Psylo Gold, 29”, 140mm, stealth boost, 42mm offset
• Rear shock: RockShox Deluxe Select Plus, 210x55
• Handlebar: 780mm wide, 20mm rise, 3deg upsweep, 6deg backsweep, bar bore 31.8mm
• Stem: 45mm extension, 31.8mm clamp
• Grips: Calibre ribbed lock-on grips
• Headset: FSA No. 57e tapered, ZS44 upper, ZS56 lower
• Saddle: Calibre trail
• Dropper post: X-Fusion Manic LC, XS&S:125mm, M:150mm, L&XL: 170mm
• Seatclamp: Alloy single bolt 34.9mm
• Chainset: Shimano Deore
• Pedals: Flat pedals
• BB: 73mm threaded BSA BB
• Chain: Shimano M6100, 118 links, 12 speed
• Cassette: Shimano, CSM6100, 12 speed, 10-51T
• Shifters: Shimano M6100-12 speed
• Rear derailleur: Shimano RD-M6100
• Front Tyre: Maxxis 29”x2.5” Minion DHF 60Tpi Exo, tubeless ready
• Rear Tyre: Maxxis 29”x2.4” Dissector 60Tpi Exo, tubeless ready
• Rims: 30mm ID, can be set up tubeless
• Front hub: Shimano HB-TC500-15-B, 110mm, 32h
• Rear hub: Shimano FH-TC500-HM-B, 148mm, 32h
• Thru-axle: M12, pitch 1.5, length 172mm, thread length: 20mm
• Brakes: Shimano BL-M6100/BR-M6120
• Front Rotor: Shimano SM-RT10, 180
• Rear Rotor: Shimano SM-RT10, 180mm

Please note: some minor specification changes may occur without notice. Any changes will use equivalent or higher quality parts.

Building your bike: Bikes purchased online are delivered boxed and will require assembly before they can be used. View the GO Outdoors Bike Assembly guide for more info, including step-by-step and video instruction guides.

We are happy to assemble your bike for FREE at any GO Outdoors store with a bike servicing department (this excludes all GO Express stores, and selected other GO locations). Please call ahead to confirm that you would like us to build your bike. You can find store details and phone numbers here. Every bike sold also comes with FREE 6 wee