The Pre-Unit Triumph Bobber Mantra

Bryan Thompson took on this build like a mountain man with a mission. He had to build a pre-unit bobber and stay true to the Triumph code. Only Triumph components could be used.

No custom frame, forks, or wheels; just a couple of traditional Bates components and the rest original.

But let’s back up first. Bryan has been a two-wheeled guru since a teenager, when he took bicycles apart and painted them. Then he moved on to Vespas, until he fell in love with speedway racing in Costa Mesa, Caifornia, and hammered the dusty track for years until his body cried for a reprieve. Then his vintage blood surfaced.

“I always admired BSAs and Triumphs,” Bryan said. He took on a rough ’66 Triumph bobber.

“But the pre-unit Triumphs had the look I was after,” Bryan said. He did his research and discovered later ’50s Triumphs contained better power, improved gear boxes, and refined clutches. He started his search.

“Thank God for swap meets,” Bryan said. “Ebay drives up prices, and you can’t tell anything about what you’re getting.” He ultimately found the ’59 frame, motor, and rear wheel at a swap meet.

He wanted the performance of the later model Triumph, but the style of the rigid. He found a stock ’52 rigid section and stretched it slightly so he could run the ’59 Triumph oil bag. But he made a special effort to ensure that every aspect appeared as if it was stock. He didn’t want any welds to show, so after welding, he hand-ground, then filled, and ground some more. No welds show and no Bondo was used.

He rebuilt the engine and added the Bonneville head for additional performance. He’s always enjoyed painting, but shooting House of Kolors candy was a new and daunting experience.

“There are over 15 coats of paint used during the finish process,” Bryan said. He started with House of Kolors primers, then sealers, then base coats, candies, clear coats, then graphics, gold leaf, pin-striping, and more clear coats.

At one point, while attempting to use environmentally friendly paints, he cleared the rear fender, and left it to dry in the shop under heat lamps. It didn’t dry for hours. He hauled it outside, and it still didn’t dry.

“I took John Kosmosky’s House of Kolors class,” Bryan said. But he forgot to add the hardener to the final clear coat. Very carefully, he cleaned the unsetting clear coat off the fender with thinners, re-mixed his clear concoction, and the fender survived.

This is one of the finest custom Triumphs we have ever run across, and his show awards prove it. Next, he will enter the San Jose, California Clubman Show devoted to British bikes.

Bikernet Magnificent Triumph Tech Chart

Owner Bryan Thompson
City: Arroyo Grande
State: California

General Info

Make: Triumph
Year: 1959
Model: TR-6 pre-unit
Type: Bobber
Fabrication: Owner
Time: 5 years
Assembly: Owner

Engine

Type: TR-6
Displacement: 650 cc
Year: 1959
Pistons: Stock
Cylinders: Original
Head: Bonneville dual-carb
Camshaft: Stock
Lifters: Solids
Carburetor: Amal Monoblocs
Air Cleaners: Dual velocity stacks
Exhaust pipes: Straight, minus mufflers

Frame

Type: Original rigid
Year: 1959
Builder: Triumph
Stretch: Stock
Rake: Stock
Swingarm: Removed and replaced it with ’52 hardtail
Mods: Swingarm extended

Paint

Molding: On frame, seat brackets and fender
Painter: Bryan Thompson
Color: Candy Apple Red, House of Kolor
Lettering and gold leaf: Dave Bond, Lucky B Design
Powder coat: Rear hub–chrome, taillight bracket–gloss black