So about frames…

The very, very first motorcycles? Those were bicycles with a motor. Literal. Then things got more serious, engines became more powerful and frames had all that power – up to 3,5 hp! – could handle. The idea about the stiffness of frames, wheelbases and steering head angles crystallized.

Attention was paid to braking.

Coming from a bicycle background, frame builders remained conservative: motorcycle frames were made of steel pipe. This approach was not only quite effective, but also easy to implement. The pipe pieces were usually brazed in cast sleeves, the 'lugs'. Because it was not always clear which alloys were best for all that buzzing, a frame sometimes broke. Although the construction dimensions were drawn safely and with a dose-estimated margin rather than calculated to three decimal places.

From the cycling world, the single cradle frame was just a small step forward. More stable frames with a double cradle were introduced. There were frames under which the engine block hung and frames of which the engine block formed a load-bearing part. Mopeds became faster and heavier.

Until now, the main goal of a frame was to be as stiff as possible in order to influence the bicycle geometry as little as possible while driving. In Italy the idea arose to combine frames that were as stiff as possible with rock-solid suspension and damping. The result was back pain, but a bike that went through the bends like it was on rails. Because there was no movement whatsoever in the frame, so that the ideal wheelbase and steering head angle drawn on paper always remained identical to practice.

The British were also famous for their roadholding in the time before the cute island finally lost its track. That had to do with the fact that on the other side of the Channel they only had second-tier roads dancing friendly through the landscape. The British motorcycles did not weigh much and, unlike their Italian counterparts, were considerably more comfortable. The nature of the local roads got in the way of really fast driving.

British circuits were driven fast and Norton was once leading there with the Roadholder front forks and the legendary Featherbed frames. Once they were released on public roads, a shock went through the motorcycle universe.

Before that, experiments had already been done with riveted steel frames (Nimbus), with pressed steel shell and monocoque frames (New Motorcycle, Escol, NSU, Honda). Frames made of pressed sheet came from the automotive world in idea and were ideally suited for real mass production. Pipes and tubes, lugs and gusset plates no longer had to be joined together.

With a few blows you had a left and a right frame 'shell' and they could simply be baked together. On the steering head, on the rear axle, on the block. Finished. Honda took the mass approach so well that the front forks and rear forks of the C72/77 were also made of pressed sheet steel.

But tubular frames remained the norm and aluminum tubular frames became exotically high-tech. But production numbers - and technical developments - grew and so came combination frames made of pressed, tubes and castings.

Meanwhile, we are in the early 70s. The Japanese have made motorcycling socially acceptable. Motorcycling is no longer something for people with too little money for a car, motorcycling is FUN! More power also means more fun. And during that period, the power of Japanese engines increased somewhat faster than their developments in bicycle technology.

In response to critical articles, the idea “Japs don't steer” arises. Like all pointless drink talk, most of the bleating was from people who had never ridden a Honda CB750 or Kawa 500 Triple. Because at Zandvoort the top players of the time set great times against those 'non-steering Japs'. It has even been documented that a Honda C72, a 250 cc sheet steel rocking horse with rocking arm front fork, stuck tightly behind a recognized razor-sharp (because stiff, rock-hard suspension) steering Ducati 175.

We are now in an era where, as models evolve, computers calculate that the frame has become 8% torsionally stiffer and the rear fork has actually become 12% less stiff.

Among the AMK readers there is a man who will hate it all: Gerard Kramer builds masterful frames according to his own ideas and at the request of customers. He does this in the most traditional way.

And then there is Jean-Pierre Jansen. He converted a sewing machine into a mini racer for his grandchild. Apparently there have been voices that this sewing machine racer is a bit too fast for the toddler...

Frame building remains an interesting subject!