First Look: BMC Fourstroke AMP LT – Powered Downcountry

If the BMC Fourstroke name sounds familiar, but the suspension layout doesn’t, that’s because the Swiss brand has totally overhauled its cross-country and marathon platform, and in case you haven’t noticed, it also added a TQ-HPR50 engine to the system, hence the AMP suffix on the model name.

The 120mm-travel Fourstroke LT AMP frame design houses the same visually undetectable, near-silent TQ motor that Trek uses in its Fuel EX-e we tested in July.

Essential Details
• Carbon fiber front and rear triangles
• APS double-link suspension design
• 120 mm front and rear travel
• TQ HPR50 reader, 360 Wh battery
• 66.5° head tube angle
• 77° head tube angle
• Sizes: S, M, L, XL
• Price: $7,299 – $14,999 USD / €6,899 – €13,999
bmc-suisse.com

Not wanting to limit the bike’s hydration capabilities despite the 360 ​​Wh battery in the downtube, BMC rearranged the orientation of the shock on the dual-link carbon fiber frame to hold two bottles of water inside the front triangle, while nesting an integrated screen in the top tube and ditching the Eightpins integrated dropper used on the unpowered version of the Fourstroke.

The Swiss are not known for creating affordable products, but they are known for their high standards. BMC has four models in the range starting at $7,200 and climbing to a price that will leave a hole in your bank account – $14,999. The bike will be delivered first in Europe, starting in December 2022 with the most expensive model. A few months later, they will be available in the USA. From there, the pattern will continue as the cheaper models arrive.


Frame and engine details

Straight, clean lines create a clean outline on the Fourstroke AMP LT with no signs of a battery or motor visible from the side view. If you take a top-down view of the frame, you’ll see the integrated TQ display screen and likely catch the charging port at the top of the downtube, out of harm’s way. In an effort to create clean lines, BMC routed the rear brake line and other necessary cables on the three lowest-priced models, through the headset cap.

In order to accommodate a wider variety of seatposts, the BMX has moved away from the integrated and exclusive Eightpins dropper post adjustment that the standard Fourstroke features. Using a 31.6mm seat tube, consumers can race with the stock post or choose from an assortment of options on the market.

As for the motor, the system is identical to the HPR50 unit that so easily snuck past unsuspecting trail users in the previous test. In total, the mechanical system assistance weighs only 3.9 kg and produces 50 Nm of torque. All changes to power output, controls and visuals will be accessible through the TQ Motor app.

Suspension design

Judging by the lines of the Fourstroke AMP LT and the short top rocker link, you could bet this frame could have been flexstayed, but BMC stuck to their kinematic goals which were only achievable by using the double-link APS configuration. BMC says the new kinematics decrease anti-squat to reduce chain growth and pedal kickback deeper into the stroke. At the same time, they added more progression to increase small bump sensitivity and more support towards the end of the travel.

Geometry

Although this lightweight, marathon-style eMTB is built with components similar to those you’d see on the XC World Cup circuit, it receives a steep 77-degree seat tube and a slightly slacker head tube angle of 66.5 degrees. All four sizes have smaller gaps between each span number, starting at 437 and jumping about 20mm per frame size, however, base lengths remain at 435 across the board.

Specifications

The Fourstroke AMP LT LTD comes complete with Fox Factory suspension, including a 34 StepCast fork and DT Swiss XRC 1200 carbon wheels, leaving little to be desired on the top-end $14,999 package which also includes matching purple paint. to the wireless oil slick. SRAM XX1 AXS components. Moving down the price scale, the AMP LT ONE’s suspension switches to RockShox, with SID and Super Deluxe Air in the Ultimate version, and DT Swiss alloy wheels, but retains SRAM G2 RSC brakes with 180mm rotors at each end.

From there, the two lower priced Fourstroke AMP LT TWO and THREE continue with RockShox suspension, but shifting and braking duties are covered by Shimano. Across the line, Maxxis Rekon 2.4” EXO tires are the choice for rubber and Praxis takes care of the cranks with alloy options.



Wiley C. Thompson