With the Legion Series, Mongoose offers a premium line of freestyle BMX bikes designed for riders looking to elevate their skills at the park, street, or dirt tracks. The Legion L40 strikes the ultimate balance in the lineup, arriving in a sleek navy colourway with a slightly extended 20.5-inch top tube that provides the perfect mid-sized geometry for growing riders. Built to shrug off the hard knocks of progressing riders, it comes loaded with performance upgrades usually reserved for more expensive rigs. Featuring a bulletproof mid-sealed bottom bracket and a 3-piece chromoly crankset, this street-ready machine offers incredible durability, smooth power transfer, and a rock-solid platform for mastering your first proper tricks and drops.
Key Features
Sealed Mid Bottom Bracket: Equipped with a sealed cartridge mid bottom bracket that significantly resists the elements and ensures ultra-smooth pedalling under heavy loads.
3-Piece Chromoly Cranks: Features robust 175 mm 3-piece tubular chromoly cranks with an 8-spline spindle for vastly superior structural strength over entry-level 1-piece components.
Extended Top Tube Geometry: Designed with an accommodating 20.5-inch top tube, giving emerging riders extra cockpit room for improved control, spin leverage, and stability.
Sealed Rear Cassette Driver: Combines a compact 25T steel chainring with a durable 9T sealed-bearing rear cassette hub for an efficient microdrive system.
High-Volume Extra-Wide Tyres: Outfitted with 20" x 2.3" high-traction tyres paired with 24 mm internal width aluminium rims to better absorb skatepark landings and prevent pinch flats.
Technical Specifications
| Component | Specification |
| Frame | Hi-Ten steel, BMX freestyle geometry, mid BB shell, 20.5" top tube length |
| Fork | Hi-Ten steel, threadless steerer |
| Crankset | 3-piece, tubular chromoly, 175 mm, 25T steel chainring |
| BB | Mid sealed bearing, 8-spline spindle |
| Chain | KMC S1 |
| Cassette | Single-speed, 9T sealed bearing cassette driver |
| Brakes | Rear aluminium U-brake and lever |
| Grips | Mongoose MushXL, 160 mm |
| Handlebar | Mongoose, Hi-Ten steel, 28" width, 8" rise |
| Seatpost | Steel, 250 mm, 25.4 mm |
| Saddle | Mongoose Unifier, 1-piece rails/post combo |
| Headset | Threadless, integrated 1-1/8", retainer bearing |
| Wheelset | Aluminium single-wall rims (24 mm ID, 36H); steel front hub (3/8" axle, ball bearing); steel rear hub (14 mm axle, sealed bearing cassette) |
| Tyres | 20" x 2.3", wire bead |
| Extras | Mongoose nylon pedals |
Why this bike is for you
You are a developing teen or pre-teen rider between 152 cm and 168 cm (5'0"–5'6") tall who has outgrown entry-level 20.25" top tube layouts.
You want a highly reliable drivetrain that requires less frequent maintenance, thanks to the upgraded mid sealed bearing bottom bracket.
You are ready to step away from casual cruising and need a properly reinforced 3-piece crank setup to start tackling skatepark ramps and street obstacles.
Why this bike may not be for you
You are a very advanced or heavier pro-level rider who needs a full 4130 Chromoly frame matrix and double-wall rims to survive massive gaps and hard street riding.
You prefer the freedom of rolling backward without pedalling in reverse, which requires an elite-level freecoaster hub rather than a traditional cassette driver.
For safety reasons bikes can not be shipped partially assembled; they must be fully built and inspected by an authorised technician prior to collection or delivery.
