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

BSA M 21

Key specifications

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

Overview

Introducing the 1956 BSA M 21: A Classic All-Rounder Step back in time to the mid-1950s, when the BSA M 21 graced the roads with its classic charm and robust capabilities. Positioned as an allround motorcycle, the M 21 was designed to cater to a wide audience, appealing to both commuter riders and weekend adventurers. With its distinctive British styling and solid build, this motorcycle captured the imagination of enthusiasts looking for reliability and a bit of nostalgia wrapped in one compelling package. The M 21 is not just a bike; it’s a testament to a bygone era of British engineering, where functionality met a flair for design. At the heart of the BSA M 21 lies a potent 591cc single-cylinder, four-stroke engine, delivering a respectable 15 horsepower at 4,000 RPM. This power source, coupled with a wet multiplate clutch and a chain final drive, provides smooth acceleration and a surprisingly lively performance for its class. The bore and stroke measurements of 82.0 x 112.0 mm give it a unique character, allowing riders to enjoy that classic thump of a single. Whether you’re navigating city streets or cruising along winding country roads, the M 21's hydraulic telescopic front suspension and twin shock rear suspension work in harmony to deliver a comfortable and enjoyable ride, making it a true companion for diverse riding conditions. The M 21 is equipped with essential features that highlight its era, including a reliable carburettor fuel system and magneto ignition, ensuring you’ll always have the spark needed for an adventure. The single cradle frame provides strength and stability, while the expanding drum brakes at both ends offer secure stopping power, albeit with a nostalgic feel that modern riders might find charming. With a fuel capacity of 11.36 liters (3.00 gallons), the M 21 is ready for longer rides, allowing enthusiasts to relish the open road without constant stops for refueling. **

Pros

    Cons

    • Classic Aesthetic: The M 21’s vintage design and styling appeal to motorcycle enthusiasts who appreciate classic British bikes.
    • Reliable Performance: The simple yet effective engine provides dependable power for both commuting and leisurely rides.
    • Comfortable Ride: With its capable suspension setup, the M 21 offers a comfortable ride over various terrains.
    • Limited Power: The 15 HP may feel underwhelming for those used to modern motorcycles with higher performance outputs.
    • Drum Brakes: The expanding drum brakes may lack the stopping power and responsiveness found in contemporary disc brake systems.
    • Maintenance Needs: As a classic motorcycle, the M 21 may require more upkeep and care compared to newer models, making it less suitable for novice riders.

    Technical details

    Source specification data

    Make
    BSA
    Model
    M 21
    Category
    Allround
    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
    Fuel Capacity
    11.36 litres (3.00 gallons)
    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