The Triumph Pre-unit Bobber by Black Cycles Australia

In a remarkable collaboration between Black Cycles Australia and PopBang Classics, a 1950 Triumph Pre-unit TR5 500cc motorcycle has undergone a breathtaking transformation. This vintage beauty, known for its pre-unit construction, was given a new lease of life and a touch of contemporary custom craftsmanship. Let’s dive into the world of this exceptional build without further ado.

The Era of Pre-unit Motorcycles

In the early 20th century, motorcycles were traditionally built by assembling a separate engine and gearbox, linked together by a primary chain case. However, in 1959, Triumph introduced a revolutionary design that integrated the crankcase, transmission, and gearbox into a single unit, setting a new standard in motorcycle construction. This unit construction was lighter, stronger, more compact, quieter, cleaner, and more cost-effective. By 1963, all Triumph motorcycles had embraced unit construction, and the earlier models became known as Pre-unit Triumphs.

A Pre-unit Revival

The story of this remarkable Triumph Pre-unit begins when Ben, a motorcycle enthusiast from Sydney, acquired a 70% complete Triumph Pre-unit with an all-alloy engine. His vision was clear: a classic Triumph with a custom ‘bobber’ twist. To bring this vision to life, Ben entrusted the project to Noel Muller of Black Cycles Australia. Given Noel’s extensive experience in crafting custom bikes, Ben’s Triumph was in capable hands. However, this endeavor required a blend of expertise from both Black Cycles and Justin at PopBang Classics on the Gold Coast, making it a true 50/50 collaboration between the two shops.

A Custom Classic

The heart of the project was the restoration of the motorcycle to classic yet custom perfection. The frame underwent meticulous modifications, including filling excess factory holes and deburring. The handlebars and risers were custom-made as a one-piece unit, featuring integrated lever perches for a clean and streamlined appearance. The peanut tank received a subtle customization with a front filler, and a motogadget mini speedo was seamlessly frenched into it. The handlebars concealed micro switches for added functionality.

Adding to the vintage appeal, a leaf-spring seat was carefully crafted and adorned with union jack upholstery. Knurled billet grips and pegs, a brass kicker pedal, a round oil tank, aftermarket upper fork covers, and hand-fabricated stainless steel header pipes with tapered mufflers were integrated into the design. The bike features flanged alloy rims with stainless steel spokes, and a custom front fender complements the ribbed rear.

Kellermann atto all-in-one micro indicators and tail lights provide both elegance and functionality. A brass fuel cap, various machined in-house caps, covers, spacers, and a 4″ bates-style headlight complete the vintage look. A finned alloy cover plate graces the seat area, while stainless steel struts support the front and rear.

The Engine and Transmission

Justin at PopBang Classics took charge of the engine and gearbox rebuilds. The engine stands out as an all-alloy version, a rarity that adds to the bike’s unique character. Justin meticulously wired the motorcycle, and his craftsmanship extended to applying gold leaf to the custom mixed green/grey paint. Additionally, Justin supplied numerous new and used parts, including electronic ignition, alternator, and rims, which he laced and trued.

A Labour of Love

This project was truly a labour of love, marked by the dedication of two skilled workshops coming together to breathe life into a classic motorcycle. The meticulous attention to detail is evident in every aspect of the build, from the elegant frame modifications to the custom paintwork and the vintage-inspired components.

Ben’s vision of a classic Triumph ‘bobber’ has been realized in a bike that not only harks back to the golden era of motorcycling but also offers a unique and contemporary twist. It’s more than a motorcycle; it’s a work of art, a tribute to craftsmanship, and a testament to the enduring allure of classic bikes. Australia’s best Triumph? You might just be looking at it. Read the full interview at BikeBound.

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