The Calibre Bossnut is our MTB of the Year because of its well-earned, outstanding legacy. Capable of going toe to toe with any other trail bike out there, it's made its mark in the industry by providing a high quality build and handling in almost any conditions, without ever compromising on quality. 

Back better than ever the 2025 Calibre Bossnut is built around a brand new frame designed from the ground up with progressive geometry that's amazing out of the box, as well as worthy of upgrades to stand the test of time. Stacked with quality components that make it more capable than ever and with the same easygoing feel that it's always been loved for.

Available online and in the following GO Outdoors stores while stocks last: Basingstoke, Berwick, Blackburn, Bury, Canterbury, Cardiff, Chester, Chesterfield, Clydebank, Coatbridge, Derby, Doncaster, Edinburgh, Erdington, Gateshead, Harlow, Hull, Inverness, Ipswich, Kidderminster, Liverpool, Loughborough, Milton Keynes, Norwich, Nottingham, Penrith, Peterborough, Plymouth, Pudsey, Shrewsbury, Stockport, Stoke, Sunderland, Swansea, Swindon, Taunton, Thurrock, Wakefield, Wigan, Wolverhampton, Coventry, Stockton and York.

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)

• Frame: 29” 6061 Alu, boost spacing, 135mm rear travel, tool and bottle bosses

• Forks: RockShox Recon Silver RL, 29”, 140mm, stealth boost, 42mm offset

• Rear shock: RockShox Deluxe Select R, 210x55

• Handlebar: 780mm, 31.8mm, 20mm rise

• Stem: 45mm, 31.8mm clamp

• Grips: Calibre 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: 34.9mm

• Chainset: Shimano Cues 32T, 170mm cranks

• Pedals: Flat pedals

• BB: 73mm threaded BSA BB

• Chain: Shimano Linkglide, LG500

• Cassette: Shimano, 10 speed, 11-48T

• Shifters: Shimano Cues

• Rear derailleur: Shimano Cues

• Front Tyre: Maxxis 29” x 2.5” Minion DHF 60Tpi Exo

• Rear Tyre: Maxxis 29” x 2.4” Forekaster 60Tpi Exo

• Rims: 30mm ID, tubeless ready

• Front hub: Shimano, 110mm, 32h

• Rear hub: Shimano, 148mm, 32h

• Thru-axle: M12, pitch 1.5, length 172mm, thread length: 20mm

• Brakes: Shimano MT401

• Rotors: Shimano 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 week safety check.

Can't get to a GO store? Our partners at LeisureLakes bikes will also assemble and inspect any new