Big Bro Complete

£1,799.00 £1,079.40 Inc VAT



Built around our tough-as-nails mountain bike frame – the Big Bro has been designed with versatility in mind. So whether you’re running a lightweight bikepacking setup, front and rear panniers for a ’round-the-world’ tour or stripped back to thrash some forest trails the Big Bro can handle it.

The frame is made out of tough 4130 double butted cr-mo tubing with a 100mm suspension corrected fork. It comes equipped with the bombproof Sram GX 1×11 groupset – providing reliable shifting in the toughest of conditions. WTB Ranger 3.0 tyres on 27.5+ wheels are a trail ready “bikepacker approved” wheelset that excels on longer rides. Last but not least the TRP Spyke mechanical disc brakes give you confidence-boosting stopping power all day long.

Like all Brother products the Big Bro was rigorously tested. We took prototypes to Snowdonia National Park, up to the Scottish Highlands and most recently bikepacking through the Bavarian Alps – we can confidently say it excelled in all conditions.



Frame Specs



Crankset: SRAM GX-1000, X-SYNC 30t
Bottom Bracket: SRAM GXP
Rear Derailleur: SRAM GX 1x11
Cassette: PG-1130 11–42t, 11-speed
Chain: SRAM PC-1110


Headset: FSA Orbit ITA
Brakes/Rotors: TRP Spyke, front 180mm rear 160mm
Brake Levers: TRP ML-800
Shifters: SRAM GX 11sp
Stem: Promax DA-296 70mm
Handlebar: MJ 133EN 730mm
Saddle: WTB Volt Comp
Seatpost: Promax SP-2016


Front Hub: Formula DC91 Disc, 32h. 100mm
Rear Hub: Formula DC32 Disc, 32h. 135mm
Rims: Alex MD40 Tubeless Ready
Tires: WTB Ranger 27.5x3.0


Please note: Your bike will arrive 90% assembled. You will need to attach the pedals, front brake, front wheel, handlebars, seat and a few other minor parts as well as adjust, tighten and tune. It is possible to build with moderate bicycle knowledge, however we highly recommend that you have your bike put together and checked by a professional bike mechanic for safety and proper functioning. Shipping direct to your local bike store for assembly is possible.


Tubing: - 4130 Chromoly steel - double-butted main triangle
Brake compatibility; 51mm IS disc brake mount, 180mm max rotor size
Dropouts: Vertical, 135mm O.L.D sliding Quick Release dropouts (optional 12x142mm Thru Axle plates available separately)
Seat post diameter: 30.9mm
Seat clamp diameter: 33.1mm
Headset: 44mm, SHIS ZS44/28.6 upper, EC44/40 lower
Front derailleur clamp diameter: 34.9 mm high direct-mount (adapter available separately)
Bottom bracket shell: 73mm bottom bracket, ISO threaded
Maximum tyre clearance: 29" x 2.4", 27.5" x 3.0"
Fork : 4130 Chromoly tapered unicrown fork, disc only
Full-length cable housing guides for derailleurs and brakes
3 sets bottle cage mounts on all sizes
Chainring clearance: up to double 42-28t, single 38t
Weight: medium (18") frame 2.6kg, fork (260mm steerer) 1.25kg

Big Bro Complete technical drawing
SizeSmall (16)Medium (18)Large (20)xLarge (22)
Seat Tube (C-T)406mm457mm508mm559mm
Top Tube (C-C)556mm571mm590mm607mm
Top Tube (Effective)575mm595mm615mm630mm
Head Tube95mm100mm110mm125mm
Head Angle69.57070.570.5
Seat Angle73737373
BB Drop60mm60mm60mm60mm
Min Chainstay445mm445mm445mm445mm
Fork Length (A-C)483mm483mm483mm483mm
Fork Rake46mm46mm46mm46mm
Standover (mid top tube)782mm810mm840mm871mm

Are your frames guaranteed?

Our frames and bikes are fully guaranteed against manufacturing and materials faults or defects for 12 months from date of purchase. This guarantee does not cover items which are damaged through accident, misuse, wear and tear, neglect or those which have been repaired or altered by any other firm. Paintwork is not covered covered by this warranty, nor is any damage that happens to you or your other components as a result of any failure of one of our products.

This guarantee is only valid to the original customer and is non-transferable. We reserve the right to an independent opinion on whether the goods qualify for a refund. A dated proof of purchase must be provided before a warranty claim will be considered.

Can you build me a custom bike?

Sorry we don’t do custom builds, but you can contact one of our many stockists for assistance in building up a bike.

Where are your frames stocked?

You can see a list of shops where our frames are stocked here. If your LBS isn’t listed then ask them to get in touch with us about ordering a frame for you.

Where are your frames made?

Our frames are made in Taiwan. They are handmade using traditional brazing and welding techniques with the highest quality materials by a team of frame builders who have over 2 decades of experience. Each frame undergoes extensive quality and safety checks before it is shipped to us in the UK. Although built overseas our frames were carefully designed by us in London and are exclusive to Brother Cycles.