First Look: The 2025 Marin Alpine Trail E Has a Bosch Motor & More Adjustability

Frame Details & Motor

The alpine Trail E Bosch has Marin's Series 4 aluminum frame and their new MultiTrac 2 LT suspension design, which uses a Horst link layout. Secured inside the downtube is a 750 Wh battery that is removable for charging off the bike. It powers the Bosch CX Performance Line motor, which boasts a maximum torque of 85 Nm and a peak power output of 600 W. That's achievable at a cadence of 70 rpm, as compared to the much higher cadences that are demanded by the Bosch SX motor that you'll see on much lighter offerings. There is no range extender option.



Geometry

The Alpine Trail E Bosch is altogether quite different to the Alpine Trail E Shimano models, in terms of its geometry and suspension platform, as well as the obvious. Developed in conjunction with the Alpine Trail enduro bike, it shares a very similar geometry. However, while the acoustic bike is available in S-XL, Marin decided to offer the eMTB in M-XL only. Reach figures are 455mm, 485mm and 515mm, respectively. Chainstay lengths are the same across the sizes, but they are adjustable in the context of a BB height change.


The frame provides two opportunities for geometry adjustment:

• Chainstay Length and BB Height: The flip-chip at the chainstay pivot raises/lowers the BB height by 7mm while simultaneously shortening/lengthening the chainstay by 8mm - it also concomitantly alters the head angle by 0.5°

• Head Tube Angle: The bike ships with a neutral headset cup, but a 0.75° offset top cup allows one to steepen or slacken the head angle

In its stock setting (as shipped), the flip-chip is in the Long and Low position giving a 443mm chainstay and a 345mm BB height, with the neutral headset cup giving a head angle of 63°. With two flip-chip positions and three steerer tube angles, there are six geometry charts to enjoy.


Marin have gone for some very steep seat tube angles. The effective angles published in the geometry charts are measured using what Marin consider to be the average saddle height for that frame size - instead of measuring it at the height of the headtube. Here are those average saddle heights: 684mm for S, 721mm for M, 763mm for L and 795mm for XL.

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Suspension Design

The Alpine Trail E Bosch has 160mm of rear wheel travel damped by a 205mm x 65mm rear shock, giving an average leverage ratio of 2.46. The leverage curve is progressive throughout, starting at a ratio of 3.05 and finishing up just north of 2.05. Both models run a custom-tuned coil shock. The more expensive E2 model gets a Fox DHX2 Performance Elite shock, while the entry-level E1 model gets a Marzocchi CR shock.

We don't have more kinematic graphs to share on this one. However, the designers tell us that, as with the Alpine Trail enduro bike, they had to move away from the linkage-driven single-pivot platform seen on the Shimano-powered models when increasing travel to 160mm. Marin say, "With MultiTrac 2 LT, the benefits of relocating the rear pivot points from the seatstay to the chainstay become apparent, as it reduces anti-rise, allowing for better chassis control while braking, more mid-stroke support, and better feel at bottom out."



Build Kits

There are two Alpine Trail E Bosch models, both of which look to appeal to riders making more budget-oriented purchasing decisions. That said, both are adequately equipped with 160mm cranks, heavy casing tires with CushCore inserts pre-installed (worth $150 USD, for anyone interested), and four-piston brakes with 203mm rotors. Riders will need every bit of stopping power they can get: claimed weight for the E2 in a size large is 27.8kg (61.2 lb), and 28 kg (61.7 lb) for the XL.

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Reviews and Tech eMTB First Looks Marin Alpine Trail E Bosch