The placement of the chain drive on the right side of motorcycles produced by some European manufacturers in the 1960s to the 1980s was primarily due to technical considerations and design choices. Here are some of the reasons behind this decision:
Transmission layout: Many motorcycles during that period featured a right-side transmission layout, where the gearbox was located on the right side of the engine. Placing the chain drive on the right side allowed for a more direct and straightforward power transfer from the engine to the rear wheel, minimizing the need for complicated transmission shafts and gears.
Frame design: The design of motorcycle frames often played a role in determining the position of the chain drive. Some manufacturers chose to design their frames in a way that accommodated the right-side chain drive more efficiently, providing better clearance and alignment. This design choice allowed for more straightforward maintenance and adjustment of the chain tension.
Exhaust system: In many motorcycles of that era, the exhaust system was located on the left side of the bike. Placing the chain drive on the right side ensured better clearance between the chain and the exhaust system, reducing the risk of contact or interference between the two.
Tradition and conformity: European motorcycle manufacturers, particularly those in countries like Italy and Germany, often had a strong sense of tradition and adherence to established design conventions. As a result, some manufacturers chose to maintain the right-side chain drive position to stay consistent with their previous models and maintain brand identity.
It's worth noting that while many motorcycles today have the chain drive on the left side, there are still exceptions to this rule. For instance, some BMW motorcycles, even in recent years, have continued to feature right-side chain drives due to their design philosophy and heritage.