If you look at any modern classic from the 1970s on, you’ll notice that dinner-plate sized disc of metal which helps you stop…
Before that – we used drum brakes – but it was the introduction of reliable disc brake systems that changed the way we stopped forever.
You may think that disc brakes have only been around for 50 or so years, but in fact the first caliper/disc brake for cars was patented back in 1902 by Frederick William Lanchester, who used this system on his Lanchester cars. More mainstream cars didn’t get disc brakes until many decades later. As per usual, it was aviation and two world wars that sped up design of the disc brake – you even found them on German Tiger tanks in the Second World War! Following their introduction on racing cars, it’s thought that the 1955 Citroen DS was the first mass-produced car to get ‘em.
It’s no surprise that racing saw the first use of discs/caliper braking systems on two wheels. It was the 1923 Douglas RA dirt track race bike that first saw such a system. The ‘RA’ came from its unique braking system which was developed and patented by the British Motorcycle and Cycle-Car Research Association (shortened on the bike to ‘RA’ for ‘Research Association.) It was actually not a true ‘disc brake system’ as we would call it today.
Instead of having calipers with pistons inside to bite the disc to slow it down, the cable-actuated RA brake pressed onto the edge of the rotating disc. The front and rear discs did increase the stopping power of the six-horsepower machine but were prone to grabbing, leading some riders to coat the friction material in oil! The experiment was short lived, it seemed as by 1925 Douglas was once again fitting drum brakes to its bikes. It would be another 46 years before disc brakes were fitted as standard to a mass production motorcycle…
In the meantime, racing bikes developed disc braking systems: most notably TT winner and bike engineer Peter Williams, in collaboration with Lockheed and Rickman. Bizarrely, it was MV Agusta that dipped a toe into the disc-brake market first on a road bike. In 1965 they used a disc-brake system on their 600 touring motorcycle, using a mechanical brake linkage. Of course, it would be Honda’s seminal CB750 which would be remembered as carrying disc brakes – at the front at least – but often these early mass produced systems weren’t quite as effective as a good, proven drum set-up – at least not in the wet!
Despite this, by the early-1970s disc brakes were seen as a desirable braking fitment – with some riders going as far as buying Dunstall conversion kits that allowed them to transform their drum brake bikes into disc brake machines, very costly, though it was. By the mid-1970s disc brakes featured on most modern road bikes as well as racing motorcycles.
Today the disc brake is still the favoured method of choice for stopping your motorcycle. Things have improved massively over those early mass-produced systems, with pad material, disc material, disc design (slotted/holed etc. for water dispersal) as well as changes to brake fluid and brake line design.
Still it’s racing which is pushing on changes: did you know that radial calipers were first used by Brembo on Eddie Lawson’s 1986 YZR500? It took a further two decades before they appeared on road bikes… Some experiments on the theme haven’t been so successful: such as Honda’s ill-fated in-board discs in the 1980s and even Buell’s Zero Torsional Load rim-mounted brakes of the late 1990s. All have been variations on the disc-brake theme in a bid to better what we already have – but without success.
For a while at least then, disc brakes and calipers are here to stay…