Brother Cycles Big Bro 2025 Frameset

Our all-purpose, tough-as-nails 29er/27.5 adventure frame – designed to take you well off the beaten track and beyond. Whether you’re building up a lightweight bikepacking rig, a fully-loaded world tourer or a stripped-back trail thrasher, the Big Bro 2025 is ready to go wherever your legs and curiosity take you.

The latest edition brings a refined mix of durability and adaptability: a heat-treated 4130 chromoly main triangle for extra strength, new rail-style sliding dropouts for a stiffer rear end, and full SRAM UDH compatibility for modern drivetrains. Add to that a new set of top-tube bag and front rack mounts, and you’ve got a frame that’s evolved with the needs of real-world riders.

Like all Brother bikes, the Big Bro is built on experience, not just engineering. Tested across the South Downs, Snowdonia, and the Scottish Highlands – and proven on ultra-distance epics like the Tour Divide and Silk Road Mountain Race – it’s a platform made to endure, explore and get a little dirty doing it. Key Features

4130 heat-treated chromoly steel frame and fork with ED coating for corrosion resistance

Boost 148 / 110 spacing with clearance for 29 x 2.6" or 27.5 x 3.0" tyres

Rail-type sliding dropouts for singlespeed or geared setups

SRAM UDH full-mount compatible rear hanger

Stealth dropper routing and extensive mounting points for racks, bottles and bags

100 mm suspension-corrected fork with triple mounts on each leg

Optional Rohloff dropout plates available for 135 mm Speedhub compatibility

Real-world tested and ISO 4210 MTB certified