The MARIN MUIRWOODS 27.5 is a bike that takes the concept of an ATB (All Terrain Bike) and packages it into a form that can be used effortlessly in everyday life.

While based on city riding, it can also venture onto gravel roads and into the countryside. The flexibility of its chromoly frame, the geometry designed for ease of handling, and the 27.5-inch wheels that fit Japanese physiques well – none of these are "overly specialized," which naturally expands your riding horizons.

You might admire full-fledged ATBs like the UNIT X or THUNDER but want to start with a more practical option.

The MUIRWOODS 27.5 is an ATB that brings the city and the outdoors closer together. It's a bike you can ride without overthinking, and before you know it, your range of activity will have expanded. That's the kind of ATB it is.

2026.MARIN MUIRWOODS27.5

【Manufacturer's Suggested Retail Price】￥123,200 (incl. tax)
【Color (1 color)】Gloss Gold
【Sizes (Approximate Height Range)】S (157-168cm), M (168-178cm), L (178-188cm)

What is an ATB? | Back to the origin of bicycles: 'Not bound by purpose'

Road, MTB, cross bikes. Modern sports bikes are meticulously optimized for specific uses, with clear "correct answers."

• Road bikes for speed
• MTBs for rough terrain
• Cross bikes for daily use

While all of them are highly refined, it's also true that they can feel "difficult to use beyond their intended purpose."

This is where the concept of the ATB (All Terrain Bike) is once again gaining attention.

ATBs don't draw lines between paved and unpaved roads. City, countryside, gravel roads, even light mountain trails. Not limiting where you ride, and handling a wide range of terrain with one bike – that's the essence of an All Terrain Bike, or ATB.

Indeed, popular ATB models at eirin include the KONA UNIT X, known for its toughness and expandability, and the BREEZER THUNDER, featuring a classic look and stability.

▼KONA UNIT X detailed article here

While both are excellent bikes that strongly embody the charm of ATBs, considering their price range and componentry, it's honest to say that some people might feel, "I'm drawn to the ATB concept, but I can't jump straight into something like this."

That's where the MARIN MUIRWOODS 27.5 perfectly fits in.

It's a bike that encapsulates the freedom of an ATB while being closer to everyday life and a more realistic option.

From city to outside, from paved to unpaved roads. The MUIRWOODS 27.5 is the ideal "entry point" to the world of ATBs.

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MUIRWOODS 27.5 Frame Design: Shaping the ATB identity

At the core of the MUIRWOODS 27.5 is a frame balance that "works even if you don't decide where to ride."

It features a chromoly frame and chromoly fork. Instead of chasing numbers for lightness or stiffness, the design prioritizes a "suppleness" and stability that becomes apparent once you start riding.

On paved roads, it smooths out bumps; on unpaved roads, it doesn't hinder tire grip, and even with luggage, handling remains stable.

As an ATB (All Terrain Bike), the ride quality is designed to not limit its use to specific scenarios.

This character is supported by a very well-balanced geometry.

The MUIRWOODS 27.5 is aimed at the sweet spot for riding comfortably between the city and the suburbs.

The head tube angle is neither too slack nor too steep. Handling is easy at low speeds, and the front end isn't overly sensitive at high speeds.

Even at city stoplights or tight corners, steering is natural, and a sense of security continues even as you pick up speed.

The wheelbase is not excessively long, striking a balance that maintains good maneuverability while suppressing wobbling during straight-line riding. On paved roads, it rides much like a cross bike, while naturally stabilizing when entering gravel paths.

The bottom bracket (BB) position is also neither extremely low nor high, eliminating the need to excessively worry about pedal strikes and providing a sense of security when transitioning directly from city roads to unpaved paths.

Through the overall assembly of this geometry, the MUIRWOODS 27.5 achieves an ATB-like ride feel that is "comfortable in the city and can extend to the countryside."

It's not designed for speed or aggressive off-road riding. Instead, it fits perfectly into the "between everyday life and adventure" zone, where most of our riding time is spent. That position is a major appeal of this bike.

The adoption of 27.5-inch wheels also pairs perfectly with this frame. Not too large like 29ers, not as aggressive as 26-inch wheels. It's especially noteworthy that this size fits Japanese body types well.

Starting acceleration isn't too heavy, and handling is gentle. You get a feeling of not being "thrown around" by the bike, regardless of height or leg strength.

The balance between light acceleration and off-road capability is excellent, allowing for nimble riding on paved roads and confident riding on unpaved roads. This size encourages you to think, "Maybe I'll take a detour today."

Delving into finer details, the MUIRWOODS 27.5 frame design is "serious where it's least visible."

One distinctive feature is the shape of the front fork ends. Instead of the typical dropouts that face straight down, it employs a design where the wheel is inserted slightly from the front.

This is not for aesthetic reasons, but a consideration for effectively absorbing the braking force of hydraulic disc brakes. It allows the entire fork to better handle the forces applied during braking, leading to a more reassuring braking feel.

Another characteristic is the abundance of bolt mounts. It flexibly accommodates fenders, racks, and bottle cages, allowing you to start simple and gradually add equipment as needed.

Furthermore, internal cable routing for a dropper seatpost is also provided. While not frequently used for city riding, it's a feature you'll appreciate when riding in the hills or on unpaved roads.

These detailed elements collectively support the frame balance of the MUIRWOODS 27.5, which "works even if you don't decide where to ride."

It incorporates all the necessary elements of an ATB while still functioning as an "ATB you don't have to overthink." This is why this bike is a seamless choice for anyone just starting to show interest in ATBs.

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Specs that enable you to 'fully utilize' it as an ATB

The specifications of the MUIRWOODS 27.5 prioritize "practicality for continued use" rather than flashy features.

First, the drivetrain uses a single front chainring microSHIFT Advent X (1×10 speed). By not overdoing the number of gears and simplifying operation, it's configured to be used without hesitation from city riding to unpaved roads.

The rear cassette features a wide gear ratio of 11-51T. The front chainring is 38T, which is slightly larger for an ATB. This combination prevents the feeling of spinning out too easily on paved roads and makes it easier to cruise at a consistent speed.

Meanwhile, the large 51T rear sprocket provides a broad range, making it less likely to feel like you "need a lighter gear" on hills, unpaved roads, or when carrying luggage.

It's designed to seamlessly transition from city to countryside. The 38T front x 11-51T rear is a practical gear setting that perfectly understands the character of the MUIRWOODS 27.5.

The brakes come standard with hydraulic disc brakes. These provide consistent stopping power with light effort, largely unaffected by weather or road conditions, which is a major advantage.

Furthermore, it's worth noting the use of different rotor sizes for front and rear (180mm front / 160mm rear). The front, where more braking force is required, is reinforced, while the rear prioritizes control.

This is a very well-balanced brake configuration, designed for city riding, unpaved roads, and downhills.

The tires are 27.5x2.35 inches, offering the voluminous feel characteristic of an ATB. They aren't excessively heavy on paved roads and provide reliable ground contact on unpaved surfaces. This tire width allows you to ride without overly worrying about road conditions, fully supporting the MUIRWOODS 27.5's "go anywhere" sensation.

To summarize the specs,

• Single front chainring reduces chain issues.
• Combination of wide tires and hydraulic discs provides stability during braking.
• Simple configuration makes replacing consumables and future customization easy.

These elements are all present, ensuring longevity.

While not a flashy spec list, it's a build that thoroughly understands "what to look for in an ATB." The MUIRWOODS 27.5, with its frame design and matching spec configuration, is a bike that can expand your horizons from everyday life.

Specifications

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Summary | MUIRWOODS 27.5 is 'the ATB you don't have to overthink'

The MUIRWOODS 27.5 is a bike that takes the concept of an ATB (All Terrain Bike) and integrates it into everyday life without making it something special.

It features the flexibility of a chromoly frame, geometry that feels comfortable riding between city and countryside, and 27.5-inch wheels that fit Japanese physiques well.

This is combined with specifications designed for "real-world use," such as a wide gear ratio of 38T front x 11-51T rear, hydraulic disc brakes (different rotor sizes front/rear), and wide 27.5x2.35 tires.

Furthermore, it offers plenty of room for expanding how you use it later, with abundant bolt mounts and internal cable routing for a dropper seatpost, even if you don't utilize everything from the start.

It's neither exclusively for off-road nor exclusively for city riding. Yet, it can comfortably venture into both.

The MUIRWOODS 27.5 is the perfect choice for anyone interested in ATBs but doesn't want to feel intimidated by their first bike.

Stepping a little outside of daily life. The MUIRWOODS 27.5 is an ATB that allows you to take that first step without hesitation.

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