750 Bonnie: 1978 Triumph T140 Desert Sled

Malle Miler: Simon Lancaster’s Triumph 750 Desert Sled…  

In 1973, Triumph introduced the T140 Bonneville as an upgraded, more powerful version of the oil-in-frame T120 (650cc) Bonnie. The original T140V carried the “V” designation for the new five-speed transmission, and it boasted a larger-bore 744cc engine (724cc in the very early models) with 54 bhp on tap. Despite gearing that favored cruising over acceleration, the 750 Bonneville ran a quarter-mile time of 13.64 seconds — quite respectable for the era. 

However, the real story was the handling, which was unexpectedly stellar for a British twin.

“Handling qualities can only be described as excellent. With one rider on board it was possible to lean the machine to either direction to an acute degree without grounding anything until the rear tire began to step out into a slide.” –Cycle World

In fact, the CW buffs went on to call the T140V “Triumph’s Best Bonneville.” They just wished it had come half a decade earlier to rival Japanese domination of the motorcycle market and keep the Brits in business a bit longer.

Even back then, as nearly vibrationless, low-maintenance machines were becoming the norm, the 750 Bonneville was something of a throwback.

“What the Bonneville has to offer is light weight, dead-accurate steering, telepathic handling, low-rpm torque, and stone-ax simplicity. It has styling strong enough to get a certain kind of rider interested, and a personality vivid enough to keep him that way. Which means that the things that made a Bonneville appealing in the first place are still going for it: It does what a motorcycle is supposed to do, and it looks the way a motorcycle is supposed to look… Those who have never thought of a multi-cylindered, water-cooled, vibration-free, dead-reliable, solid-state motorcycle as a lifeless refrigerator — will never understand.” -Cycle Guide

Today, the T140V, which cost $1599 in 1973, remains one of the better deals in the vintage Triumph market. The one you see here comes from our new buddy Simon Lancaster (@simonmoto1), a “64-years-young” Brit who’s been riding for more than 50 years. However, it was only in the last decade or so that Simon began customizing bikes to a significant degree.

“The trigger for my journey into customising bikes was all the fault of Jonny and Robert of Malle Mile fame!  I went to one of the early Malle Mile events, loved the concept, and for the next year’s event built a Suzuki SV650 scrambler.

“Since then have been to every one! Things changed when I rode an old British Triumph and that was it — I bought a Triumph T140, my preferred Triumph. I loved the desert sled/flat tracker style and went from there.”

Simon is quick to say that he’s no master fabricator — in fact, he says he considers himself more of a “stylist” than a builder.  That said, we love a bike that’s built to ride, not show, and Simon’s 750 desert sled was one of favorite machines at the 2026 Malle Mile. 

The Malle Mile 2026: In Dust We Trust!

Simon stripped down the standard bike to make it as light as possible — at 414 lbs dry, the stocker itself was already considered quite light for a 750. He’s not sure of the current weight, but it should be sub-400 lbs with the bare-bones bodywork and total-loss ignition system. 

There’s a custom seat, alloy rear fender, Twin Air foam filters with custom-made adapters, and a set of high-mounted open pipes that sound glorious at full song. Simon played with the stance and geometry, lowering the front end internally and opting for slightly longer rear shocks to level out the bike, giving it more of a street tracker or TT stance.

The US-spec tank has plenty of patina, and the whole bike oozes character…especially when you see it tearing up the grounds of Grimsthorpe. 

“The bike is awesome to ride, light, responsive, and with the open pipes sounds awesome…”

Thanks to Simon for sharing his Malle Mile desert sled, and Roberto Garagarza (@roga______) for all the great shots of the bike. Below you’ll find our full interview with Simon about the build, along with more details and photos. 

750 Bonneville Desert Sled: Builder Interview

• Please tell us a bit about yourself, your history with motorcycles, and your workshop.

Simon Lancaster, 64 years young, have been riding motorcycles since the age of twelve, first bike being a Fantic 50cc scrambler.

The trigger for my journey into customising bikes was all the fault of Jonny and Robert of Malle Mile fame!  I went to one of the early Malle Mile events, loved the concept, and for the next year’s event built a Suzuki SV650 scrambler.

Since then have been to every one! Things changed when I rode an old British Triumph and that was it — I bought a Triumph T140, my preferred Triumph. I loved the desert sled/flat tracker style and went from there.

There are some amazing, talented custom builders around who do some amazing work with fabrication, etc. I wish i was that talented; I just have a vision in my head of what I like a bike to look like and build it with what I have. I like to consider myself more of a “stylist” than a builder 🙂

My workshop is a standard single garage with all the tools I need (most of the time)…

• What’s the make, model, and year of the donor bike?

Make of bike is a Triumph T140V, 1978.

• Why was this bike built?

The bike was built for the Malle Mile, Malle Beach Race, Heritage Sprint, etc. — but also for road use and green laning.

• What custom work was done to the bike?

The standard bike is stripped of all parts not needed to make it as light as possible. A total loss ignition system was fitted, which generates spark only. There’s a custom seat, alloy rear mudguard, road-legal aggressive pattern tyres are fitted, and open twin left-exit pipes.

I think it’s important how a bike sits, so the front is lowered internally and slightly longer shocks were fitted to make the bike sit lower and level. Also the wheelbase was made as long as possible  with the available travel on the standard swingarm, just changing gearing or using a longer chain.

The tank is a standard American-spec tank painted satin black, with patina added! I have nickel-plated tanks in previous builds, which does look very nice. Wide western bars are fitted, and it’s running Twin Air foam filters on custom-made adapters… I guess it’s a scrambler/ desert sled with the stance of a flat tracker bike.

• Can you tell us what it’s like to ride this bike?

The bike is awesome to ride, light, responsive, and with the open pipes sounds awesome…

Follow the Builder

• Instagram: @simonmoto1
• Photography: Roberto Garagarza (@roga______)

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