Big Bro is a frame tailored for tough adventures, for those who take bikepacking seriously. Made from CrMo steel to endure multiple laps around the world. This model has completed two of the toughest endurance races in the world – the 441.8-mile Tour Divide from Canada to Mexico and the 171-mile Silk Road Mountain Race in Kyrgyzstan.

New for 2025, Big Bro is now an even more capable adventure frame – heat-treated 4130 CrMo main triangle, new configuration of sliding dropouts for a stronger and more reliable rear end, UDH full mount-compatible derailleur hanger, top tube mounts, and additional front mounts for racks.

The frame is now made from extra durable, heat-treated 4130 double-butted cro-mo tubes and comes with a 100 mm suspension-corrected fork, both with corrosion-resistant ED coating. Big Bro has Boost spacing, which means there is room for large 27.5 x 3″ tires or 29 x 2.6″ tires if you prefer a 29-inch setup. It features hidden dropper routing, multiple rack and bag mounts, a bottle mount on the seat tube, and triple mounts on and under the down tube for extra bottles and storage. The Big Bro fork also has triple mounts for additional bottle holders or Anything Cages.

The rear triangle has S-shaped chainstays with replaceable aluminum thru-axles for geared or single speed setups. These have been redesigned for 2025 and now feature a rail system for extra strength and reliability.

We think it’s fun that Brother Cycles has made a frame with Boost spacing that you can ride both geared or single speed! You can also choose between 27.5" and 29" tires depending on the terrain the bike will handle.

From experience, we can advise that maximum tire volume of 3" requires a single chainring up front; with a double, the chain will rub on the tire.