First Look: BMC Fourstroke AMP LT – Downcountry Motorized

By abbasanwarinfo Last updated Oct 17, 2022

If you’re familiar with the BMC Fourstroke name but not the suspension layout, that’s because the Swiss company has completely changed its cross-country and marathon platforms. In case you didn’t notice, they’ve also added a TQ-HPR50 motor to the system, which is why the model name ends in “AMP.”

The 120 mm travel Fourstroke LT AMP frame has the same TQ motor that Trek uses in their Fuel EX-e, which we tested back in July. This motor is almost silent and can’t be seen.

Even though the bike has a 360 Wh battery in the downtube, BMC moved the shock on the dual-link carbon fiber frame so that it could hold two water bottles in the front triangle. They also put an integrated display in the top tube and got rid of the Eightpins integrated dropper that was on the unassisted Fourstroke.

The Swiss aren’t known for making products that are easy on the wallet, but they are known for having high standards. BMC has a range of four models, with the least expensive one costing $7,200 USD and the most expensive one costing $14,999 USD. The bike will be sent to Europe first. The most expensive model will be sent there in December 2022. In a few months, they will be sold in the United States. From there, the pattern will keep going as cheaper models start to come out.

Frame and engine specifics

The Fourstroke AMP LT has clean lines that are straight and sharp. From the side, you can’t see a battery or a motor. If you look at the frame from the top, though, you’ll see that it has an integrated TQ display screen and that the charge port is hidden at the top of the downtube. In order to make the bike look neat, BMC ran the rear brake line and other necessary cables through the headset cap on the three cheaper models.

BMX got rid of the integrated and proprietary fit of the Eightpins dropper post on the standard Fourstroke so that it could fit a wider range of seat posts. With a 31.6mm seat tube, customers can use the stock seat post or choose from a number of other options.

First Look BMC Fourstroke AMP LT - Downcountry Motorized — First Look: BMC Fourstroke AMP LT – Downcountry Motorized

As for the motor, the system is the same as the HPR50 unit that snuck past trail users without them knowing during our last test. In total, the mechanical system’s help only weighs 3.9 kg and makes 50 Nm of torque. The TQ Motor app will let you see all of the changes to power output, controls, and how things look.

Based on how the Fourstroke AMP LT looks and how short the upper rocker link is, you might think that this frame could have had a flex stay pivot, but BMC stuck to their kinematic goals, which could only be met with the APS dual link configuration. BMC says that the new kinematics reduce the anti-squat to stop the chain from growing and move the pedal kickback to a later point in the pedal stroke. At the same time, they’ve made the progression more gradual to make the bike more sensitive to small bumps and added more support at the end of the trip.

Geometry

This lightweight, marathon-style eMTB is made with the same kind of parts you’d see on the XC World Cup circuit. However, the seat tube angle is steeper at 77 degrees, and the head tube angle is a little bit more relaxed at 66.5 degrees. There are smaller gaps between the four sizes’ reach numbers, which start at 437 and go up by about 20mm per frame size. However, the chainstay length stays the same at 435 for all four sizes.

Specs

The Fourstroke AMP LT LTD has Fox Factory suspension, including a 34 StepCast fork, and carbon DT Swiss XRC 1200 wheels. The $14,999 top-end package leaves little to be desired, as it also comes with purple paint that matches the wireless oil-slick SRAM XX1 AXS parts. The AMP LT ONE gets a RockShox suspension with a SID and Super Deluxe Air in the Ultimate version, as well as DT Swiss alloy wheels, as the price drops, but the SRAM G2 RSC brakes with 180mm rotors at each end remain the same.

From there on, the Fourstroke AMP LT Two and Three’s two lower price points will still have RockShox suspension, but Shimano will take care of shifting and stopping. Maxxis Rekon 2.4″ EXO tires are the best choice for tires across the board, and Praxis’s alloy cranks are a good choice for the pedals.

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