bc40

Shimano XT M8100 Bike

Current lead time 4 - 6 weeks.

Regular price $5,755

The BC40 was over two years in the making. Inspired by the now-legendary Back 40 trail system, it’s a thoughtfully engineered, modern cross-country machine. That means race-day lightness and sharp handling combined with all-day comfort and control. We tested and refined this bike right in our own backyard. The rocky ledges, dynamic corners, rolling climbs, and ubiquitous jumps and flow features informed the design. The BC40 sports 120mm of front and rear travel combined with a second-to-none pedaling platform for efficient pedalling performance. Progressive geometry ensures good weight balance for both climbing and descending along with stability at speed and through sketchy portions of trail.

The Shimano XT M8100 Bike is our least expensive BC40 offering, and it is a real workhorse, anchored by the venerable Shimano XT 12-speed mechanical groupset. Perhaps you’re wary of the electronic offerings from SRAM or perhaps you’ve been a die-hard fan of Shimano’s trigger shifter sensation for many years. Either way, this bike offers smooth reliable shifting and what many folks consider to be the best braking performance in the industry. 


  • Recent improvements include 100g weight savings, stiffer front triangle, stronger and more durable, co-molded bottom bracket insert, and a co-molded alloy insert for the main pivot bearing bores that improves bearing life and ease of maintenance
  • In-house development and testing that included building our own testing methodology and machines as well as testing our competitors' bikes to benchmark performance and tearing them apart to weigh each component item
  • Designed to stretch the capability of what a cross-country bike can do while making no compromises with weight and pedaling efficiency 
  • Aluminum suspension linkage, left-side dropout interface/brake mount, and cable management inserts machined in house to ensure the highest precision for alignment and component fitment
  • Built to exceed the expectations of multi-time Olympians and national champions, for ultimate performance at the highest level of competition
  • Inspired by decades of riding and racing, and purpose-built for the hundreds of miles of trails in our backyard

Key Features


FRAMESET WEIGHT
1950 grams (Lrg)
GEOMETRY
A slacker front headtube angle for predictable handling at speed across buff and technical terrain. A longer front-to-center measurement shifts the weight of the rider further behind the front wheel for more control to maneuver at high speeds.
SUSPENSION
Designed for 120mm front and rear travel, can be adjusted down to 100mm for optimal terrain performance. Faux bar system (four bar flex stay) kinematic designed for pedaling efficiency.
COMPATIBILITY
Cable management at the headtube allows for easy compatibility across components, including dropper posts and remote lockouts.
BOTTLE MOUNTS
Capable of carrying 2, 1 on the downtube and 1 on the seat tube
TIRE CLEARANCE
29x2.4

Build Kit

BOTTOM BRACKET
Shimano XT BB-MT8000 BSA
BRAKES
Shimano XT BR-M8100 180mm/160mm
CASSETTE
Shimano XT CS-M8100 12spd 10-51
CHAIN
Shimano XT CN-M8100 12spd
CRANKSET
Shimano XT FC-M8100-1
FRONT DERAILLEUR
N/A
HANDLEBAR
FSA SL-K MTB Carbon
HANDLEBAR TAPE
ESI Chunky
REAR DERAILLEUR
Shimano XT RD-M8100 12spd SGS
SADDLE
Selle Italia Novus Boost
SEATPOST
Fox Transfer Performance 31.6
SHIFT LEVERS
Shimano XT SL-M8100-1-R 12spd
STEM
FSA Gradient
TIRES
MAXXIS Rekon 29x2.40 WT EXO/TR Tan Wall
WHEELSET
Industry Nine 1/1 Trail S Wheelset

Sizing Guide

SM MD LG XL
Crankset 170 170 175 175
Stem 40 50 50 50

Frame Geometry

SM MD LG XL
A. Stack 598 609 622 633
B. Reach 420 445 475 501
C. Front Center 710 739 775 806
D. Seat Tube Angle 76 76 76 76
E. Wheel Size 29" 29" 29" 29"
F. Headtube Angle 66.5 66.5 66.5 66.5
G. Fork Rake 44 44 44 44
H. Head Tube Length 95 105 120 135
I. Bottom Bracket Drop 40 40 40 40
J. Wheelbase 1145 1174 1210 1241
K. Chainstay Length 435 435 435 435
L. Horizontal Top Tube 569 596 630 659
M. Seat Tube Length 395 420 450 500
Have a Question?

Lighter and Stiffer

The BC40 is now 100g lighter than before. We optimized the carbon laminate schedule to carve out any excess weight that we could, and we did it without sacrificing the strength or stiffness of the frameset. In fact, the rear triangle is now stiffer than before. This means that all of your power gets to the ground as you fly up the climbs.

Bottom Bracket and Main Pivot Upgrades

Along with the laminate optimization, we’ve made some behind-the-scenes upgrades to the BC40 bottom bracket and main pivot. Both changes involve co-molded aluminum parts that ease maintenance and increase durability. The new bottom bracket allows easier access for cable routing - a boon to home and shop mechanics alike.

Chainguide

The BC40 gets its long awaited chainguide. It’s a small thing, but it makes a big difference. While clutch-type derailleurs and narrow/wide chainrings do an admirable job with chain retention, sometimes one needs that little bit more confidence. This chainguide bolts right to the existing receiver on the pivot axle. Max 34t chainring.

Ultralight DUET Bar/Stem

DUET is a handlebar and stem system that rivals or betters the weight of most one-piece cockpit systems, yet you still get the adjustability of a traditional two-piece system. Both bar and stem are among the very lightest in the market. The 780mm DUET Handlebar paired with the 50mm DUET Stem totals a scant 199 grams.

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