Stories of Motorcycle Design:

The Bonneville TT

I designed it as a replacement for the 1971 Bonneville. It became a triple instead.

Chapter 2: Making the Bonneville TT

What I did the summer of 1972

In 1969, American management asked me to "Americanize" the BSA Rocket 3. In 1971, before the Hurricane was introduced, I was asked to redesign the Bonneville. English management was still not sure about my work. Didn't Bert Hopwood write, (about the Hurricane) in "Whatever Happened to the British Motorcycle Industry":

"It had been styled by Craig Vetter, a young American, to appeal to what I can only describe as the "Trendy" type of rider whose numbers were increasing fast in the States"

1968 BSA Rocket 3
1972 Vetter Hurricane
(This was the same bike!)

The Hurricane was not even released yet and they were giving me the Bonneville project.

I considered the Triumph Bonneville to be an English Treasure.


When Jack Redmond called, we still had separate BSA and Triumph motorcycles competing in the marketplace. There needed to be continuing differences between the marks. BSA motorcycles were already more flashy with their chrome tanks. The new Hurricane would fit right in as a BSA. Jack confirmed that the Triumph should continue to be the more conservative of the two.

Jack sent me two of the new gold and white, 1972 Triumph Bonnevilles, one to ride, one to redesign.

"Bring it into the future, make it American, but also British" Jack Redmond, 1972
"Domesticating" Gene Romero's TT Triumph Making it street-legal
It would need instrumentation. The new rubber instrument mounts did a good job of protecting the gauges. But it did not take long for them to begin to sag and look sloppy.
The new instruments began to sag right out of the box
Actually, they began sagging inside the box. I had a better idea. The Big Vincent meter always looked good to me. It was aimed at the rider, so he could see it, too.

How thoughtful.

I loved the big Vincent meter
I would make the Bonneville TT meters big and make them adjustable.
I put the horn between the meters so they could blast into an offender's ear. Strong, metal rings floated the meters in rubber. Right angled drives might be OK but I eventually decided to use the tach and speedo cables as bold elements of the design.

A motorcycle is a collection of beautiful parts.

Why hide the cables?

Returning the tank to its "Slender" Edward Turner tradition
The stainless steel fender made it look British again. Now I could begin working on the tank

(I love those black metal fender stays)

See the big tube between the tank shapes? That is the "Oil-in-the-Frame" thingie that made everything high. I was forced to drop the tank down right over it. There wouldn't be much room left to hold the petrol*. But I had to get rid of the height.

* I have heard rumors that the Hurricane's tank did not hold enough petrol either.

Tank shape studies
CAD: Cardboard Aided Design

Cardboard attached to the Masonite sides with hotmelt glue provided a rough mandrel for the clay. I add clay, scrape it until it looks and feels right.

The proper way to design a motorcycle It doesn't get better than this
Americans and British riders have a fondness for teardrop shaped tanks: Round at the front and pointed at the rear. The teardrop tank was essential in recapturing the Classic quality of my Bonneville TT.
About this time, I received this letter from a graduating design student named Charly Perethian:
Charly's timing was perfect. I needed help building the Bonneville TT. We met. He was odd like me. We understood each other. Charly came to work and fit right in. Today, Charly Perethian continues to design and build motorcycle accessories for his company Parabellum
Developing a TT- like air intake system in cardboard.
This was a very straightforward solution. Two big filter elements, like on Romero's TT bike, drew air from a plenum under the seat. I took the liberty of placing the battery in there, too. Fresh air was drawn thru a snorkle under the seat. It would have been quiet and very efficient.

This cardboard mockup helped us to visualize how it would all work. Charly and I made up everything. Neither of us had ever worked for anybody before.

The Wonderful Canister Muffler
Maybe the greatest innovation on the Bonneville TT was the cannister muffler. It looked like the classic Bonneville mufflers... but they were connected together under the engine to create a huge volume to slow the gasses down.
Charly mocking up muffler in cardboard
Triumph engineers were very worried about meeting the new sound requirements. The TT muffler was huge!

Honda did exactly this three years later on the GL1000

I thought it looked "powerful"
What should the tail light look like?
Traditional Triumph
A hodge podge of parts with still no nice way to put on turn signals.
Sketch for my Bonneville TT tail light assembly

The DOT would be requiring bigger tail lights soon but we did not know the actual size. So, I measured every existing Japanese tail light and made mine bigger. I put a grab rail around it to protect it and raised it up so cars could see it over their hood.

Vetter Bonneville TT
Meanwhile, what color should it be?
I recall being told that blue was the traditional color for Triumph. I tried blue but didn't like it, so we painted it black. Charly is finishing up the classic scallop striping. Note the recessed fuel cap. The hinge was at the rear. There would be no way the cap could open in a crash and hurt anybody
Posted March 24, 2009

Updated April 2, 09

Chapter 1: Origins of the Vetter Bonneville TT
Chapter 2: Making it Real
Chapter 3: The Bonneville TT in England 2009