Mountain bike on a gray background

XC Race

BC40

BC40 SRAM XX SL Eagle Transmission Bike

Build your BC40

XC Race

Build Your BC40
BC40
BC40 SRAM XX SL Eagle Transmission Bike

It's the ultimate cross-country racing bike, stacked with premium specs, so all that's left is for you to bring the legs. Go flat out with SRAM's pinnacle MTB groupset, Flight Attendant, and the 1ZERO wheelset.

Bike image may not reflect actual build selections

XC Race

Build Your BC40
BC40
BC40 SRAM XX SL Eagle Transmission Bike

It's the ultimate cross-country racing bike, stacked with premium specs, so all that's left is for you to bring the legs. Go flat out with SRAM's pinnacle MTB groupset, Flight Attendant, and the 1ZERO wheelset.

  • SRAM XX SL Transmission Build
  • Carbon 120mm frame
  • SRAM Flight Attendant

Your build highlights

These components are required:

Your total:

Your total:

Lifetime Warranty

Every ALLIED frameset is backed by our lifetime warranty.

Flexible Payments

Finance with Affirm or use your HSA/FSA benefits. Yes, our bikes are eligible.

30-Day Returns

Buy with confidence — return within 30 days for a refund or exchange.

RACE-DAY LIGHT, PLAY-DATE READY

Inspired by the rocky surfaces, dynamic corners, and punchy climbs of our legendary Back 40 trail, BC40 is a second-to-none, modern XC racing bike with legs to take on much bigger trails. Its lightweight, high-performance carbon frame and progressive geometry deliver fast accelerations and race-day sharpness. Its World Cup talent extends to the 120mm suspension travel that also sets it up as a do-it-all weekend trail sled, delivering uncanny levels of control and confidence beyond its category.
BC40 MODEL OVERVIEW

CHOSEN BY THE BEST

World Cup athlete and World Champion Kate Courtney trusts BC40 to race to peak performances every time she takes to the start line. And no matter the build you chose on your BC40, you’ll experience the same high-performance frame ridden by the world’s best.

The SRAM XX SL Transmission Build

This BC40 leaves nothing to the imagination with this dream setup. Equipped with SRAM's top-tier wireless Transmission group, dropper, and power meter, it's the racer's weapon of choice when peak performance is the only option. Zipp's 1ZERO HITOP SW MTB wheels balance XC speed with trail durability, and TyreWiz 2.0 gets you dialed in to apply the perfect pressure on course.

Fewer decisions. Fewer distractions. SRAM’s Flight Attendant is the world’s smartest damping system, utilizing machine-learning to automatically adjust suspension performance for the ultimate, dialed-in ride. That equates to less time thinking about what you need to get the most out of BC40 and more time enjoying putting it and yourself through the wringer on every ride. Learn more about Flight Attendant.

  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike
  • BC40 SRAM XX SL Eagle Transmission Bike

The specs below reflect the default Build Kit and do not account for customizations made in the Bike Builder. See your Build Summary above for custom choices.

Fork RockShox SID Ultimate Flight Attendant 120
Front derailleur N/A
Rear derailleur SRAM XX SL Eagle Transmission
Shift levers SRAM AXS Pod Ultimate
Cassette SRAM 1299 XX SL Eagle 10-52
Chain SRAM XX T-TYPE Flat Top
Crankset SRAM XX SL Eagle Transmission Power Meter
Bottom bracket SRAM Dub 73 BSA
Brakes SRAM Motive Ultimate Stealth 4 Piston 180 Front / 160 Rear
Handlebar ALLIED Duet HB08 Carbon Flat Bar
Handlebar tape ESI Chunky
Stem ALLIED Duet
Saddle Selle Italia Novus Boost Superflow
Seatpost Rock Shox Reverb AXS
Wheelset Zipp 1Zero HiTop SW Carbon
Tires Vittoria Mezcal XC Race 29x2.4 Tires
Geometry

For optimal performance and control on fast and technical tracks, BC40 uses a slack head tube angle and a long front-to-center measurement. The result is geometry that positions the rider further behind the front wheel for world-class ride quality and predictable handling, no matter how hard you push it.

Technical drawing of a MTB bicycle frame with labeled parts on a white background
All units are in Millimeters or Degrees
SM MD LG XL
a Stack 598 609 622 633
b Reach 420 445 475 501
c Effective top tube 569 596 630 659
d Seat tube length 395 420 450 500
e Head tube length 95 105 120 135
f Head tube angle 66.5° 66.5° 66.5° 66.5°
g Seat tube angle 76° 76° 76° 76°
h Bottom bracket drop 40 40 40 40
i Chainstay length 435 435 435 435
k Wheelbase 1145 1174 1210 1241
m Fork rake 44 44 44 44
n Front center 710 739 778 806
o Wheel size 29 29 29 29
Size Guide

This chart offers a general size recommendation based on height. Since fit is personal, our team can help dial in the right size using your measurements and current bike geometry. Contact us at support@alliedcycleworks.com for a custom fit recommendation.

Small Reach: 420mm
157cm 5'2" - 167cm 5'7"
Medium Reach: 445mm
162cm 5'6" - 177cm 5'10"
Large Reach: 475mm
172cm 5'9" - 188cm 6'0"
X-Large Reach: 501mm
180cm 5'11" - 195cm 6'5"
Frequently Asked Questions

You’ll find detailed FAQs, sizing guidance, and support resources in our Help Center.

Quite simply, we love mountain biking.  It’s in our DNA, and we are lucky enough to live/work in the mountain bike mecca of NWA.  Just like the ECHO and ABLE, we built a bike that we wanted to ride, inspired by our local terrain and the demands our athletes require to perform at the highest level.

We try our best to accommodate custom options. Please reach out to us and we will let you know if it is possible and give you a quote.

Yes, all of our bikes and models ship set up tubeless with Orange Seal sealant.

No, since everyone's proportions are different, we prefer to have a human involved. Please email our fitting team at support@alliedcycleworks.com and we will custom fit you via your measurements and current bike geometry.

See exploded view HERE

The BC40 is set up with and designed around 120mm travel front and rear. It can also be set up with 110mm or 100mm options by utilizing different fork and shock options. You will see our athletes using the BC40 in 100mm travel mode for races like Leadville this summer.

The BC40 frame was designed, prototyped, and fully tested in-house at our factory in Bentonville, AR.  The carbon layup and molding on the front and rear triangles take place at an external factory based in Asia. Each raw carbon part produced at the external factory undergoes a rigorous in-house quality inspection and paint preparation to ensure the highest standards. The suspension link, brake mount, and DUET stem are manufactured fully in-house at our Bentonville location. Finally, the frame is custom-painted and assembled to each customer’s unique order at our Bentonville facility, and goes through a final inspection and test ride before leaving the factory.

29x2.4” on all sizes.

We will offer options with SRAM, Shimano, Fox and RockShox so each rider can build their own dream bike.

Target frame weight including Sid Luxe Ultimate shock is 1950g/4.3lbs for size L; final weight will vary depending on size and paint option selected.

Like all ALLIED bikes, the BC40 is built to customer order. Each rider can choose from one of our many base and logo color options. Additionally, we hope to offer a couple of our athletes’ custom paint jobs as limited editions.

See attached for the BC40 Geo and Frame Specs.

All frame sizes have a 705mm (27.8") standover measured from the center of the bottom bracket to the top of the top tube.

Please reference our BC40 Saddle Height Guide for minimum and maximum saddle heights per dropper length.

Absolutely! Click here.

73mm English Threaded BSA

We spec it around the Chris King Dropset 3:

  • 41mm 45x45 upper bearing
  • 52mm 36x45 lower bearing

Two! One of any size on the downtube, and one 21oz or less on the seat tube. Double-check that your lid doesn't rub the shock mount and the base doesn't touch the downtube—you don't want it to rub your beautiful paint!

Support
BC40 Exploded Schematic 1 BC40 Torque and Grease Protocol

Other Build Kits