Back to Bike FinderYears: 1956 · 1955 · 1954 · 1953
BSA M 21
1954Allround

BSA M 21

Key specifications

Engine
591 cc
Power
15 HP
Weight
180 kg
Fuel type
petrol
Fuel capacity
3.0 L
Front brakes
Expanding brake (drum brake)
Rear brakes
Expanding brake (drum brake)

Overview

Introducing the 1954 BSA M 21: A Classic Allrounder The 1954 BSA M 21 stands as a testament to British motorcycle engineering during the post-war era, capturing the spirit of adventure and practicality that defined the era. Positioned as an allround motorcycle, the M 21 was designed to cater to a wide range of riders, from those seeking a reliable daily commuter to enthusiasts yearning for weekend escapades. With its robust construction and timeless styling, this motorcycle embodies the essence of mid-20th century craftsmanship, making it an enduring favorite among collectors and vintage motorcycle aficionados alike. Engine Performance and Riding Characteristics At the heart of the M 21 lies a muscular 591 cc single-cylinder, four-stroke engine, delivering a respectable 15 horsepower at 4,000 RPM. This power, while modest by modern standards, is perfectly suited for the bike's intended purpose, offering a smooth and torquey ride that is both enjoyable and confidence-inspiring. The bore and stroke dimensions of 82.0 x 112.0 mm create a harmonious balance that favors low-end torque, making it ideal for urban commuting and leisurely country rides. With a wet multiplate clutch and chain final drive, the M 21 provides a seamless transmission experience, ensuring that each ride is as engaging as it is accessible. The kick starter adds a touch of nostalgia, inviting riders to connect with the machine in a way that electric starters simply can’t replicate. Key Features and Technology The BSA M 21 showcases a blend of straightforward engineering and functional design. Its single cradle frame combines strength and lightness, making it agile and easy to handle, while the hydraulic telescopic front suspension and twin-shock rear suspension provide a comfortable ride over various terrains. The expanding drum brakes, both front and rear, offer reliable stopping power, ensuring that safety is paramount while navigating the roads. With a fuel capacity of 11.36 liters, riders can enjoy extended journeys without the constant worry of refueling. The M 21 is not just a motorcycle; it’s a reliable companion for those who appreciate the art of classic riding. **

Pros

    Cons

    • Classic Aesthetic: The M 21's vintage design and polished features evoke nostalgia, making it a standout at any motorcycle gathering.
    • Simple Maintenance: With straightforward mechanical components, the M 21 is relatively easy to maintain, appealing to DIY enthusiasts and those new to motorcycle care.
    • Comfortable Ride: The combination of its suspension system and ergonomic design delivers a comfortable riding experience, perfect for long journeys or daily commutes.
    • Limited Power: With only 15 horsepower, the M 21 may struggle to keep up with modern traffic speeds, requiring riders to be more cautious on highways.
    • Drum Brakes: While reliable, the drum brakes can lack the stopping power and responsiveness found in modern disc brake systems, potentially reducing confidence for new riders.
    • Kick Start Only: The absence of an electric starter can be a challenge for some, especially in colder climates or for those less experienced with kick starting techniques.

    Technical details

    Source specification data

    Make
    BSA
    Model
    M 21
    Category
    Allround
    Starter
    Kick
    Power
    15.00 HP (10.9 kW)) @ 4000 RPM
    Clutch
    Wet multiplate
    Ignition
    Magneto
    Fuel System
    Carburettor
    Bore X Stroke
    82.0 x 112.0 mm (3.2 x 4.4 inches)
    Displacement
    591.00 ccm (36.06 cubic inches)
    Engine Details
    Single cylinder, four-stroke
    Transmission Type Final Drive
    Chain
    Dry Weight
    180.0 kg (396.8 pounds)
    Fuel Capacity
    11.36 litres (3.00 gallons)
    Power Weight Ratio
    0.0833 HP/kg
    Seat
    Dual
    Wheels
    Spoked
    Rear Tyre
    3.25-19
    Frame Type
    Single cradle
    Front Tyre
    3.25-19
    Rear Brakes
    Expanding brake (drum brake)
    Front Brakes
    Expanding brake (drum brake)
    Rear Suspension
    Twin shock
    Front Suspension
    Hydraulic telescopic