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While reading the thread about front/rear brakes, it got me thinking about something.
When did they start putting dual front brakes on bikes?
I ask because in high school, I had a friend whose family were big Norton fans. His dad and older brothers all rode Nortons, and they were modifying them with dual disks. This was in 71,72. I don't remember seeing other bikes at that time with two disks.
 

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WIKIPEDIA:

"Motorcycle Applications:"

The first motorcycles to use disc brakes were racing vehicles. MV Agusta was the first to offer a front disc brake motorcycle to the public on a small scale in 1965, on their relatively expensive 600 touring motorcycle, using a mechanical brake linkage.[17] In 1969 Honda introduced the more affordable CB750, which had a single hydraulically-actuated front disc brake (and a rear drum brake), and which sold in huge numbers.[17] Disc brakes are now common on motorcycles, mopeds and even mountain bikes."





Lambretta introduced the first high-volume production use of a single, floating, front disc brake, enclosed in a ventilated pressed-steel shroud and actuated by cable, during 1964 on their range-topping GT200 scooter.[19][20][21][22] The 1969 Honda CB750 introduced hydraulic disc brakes on a large scale to the wide motorcycle public, following the lesser known 1965 MV Agusta 600, which had cable-operated mechanical actuation.[17][23]

Unlike car disk brakes that are buried within the wheel, bike disc brakes are in the airstream and have optimum cooling. Although cast iron discs have a porous surface which give superior braking performance, such discs rust in the rain and become unsightly. Accordingly, motorcycle discs are usually stainless steel, drilled, slotted or wavy to disperse rain water. Modern motorcycle discs tend to have a floating design whereby the disc "floats" on bobbins and can move slightly, allowing better disc centering with a fixed caliper. A floating disc also avoids disc warping and reduces heat transfer to the wheel hub. Calipers have evolved from simple single-piston units to two-, four- and even six-piston items.[24] Compared to cars, motorcycles have a higher center of mass:wheelbase ratio, so they experience more weight transfer when braking. Front brakes absorb most of the braking forces, while the rear brake serves mainly to balance the motorcycle during braking. Modern sport bikes typically have twin large front discs, with a much smaller single rear disc. Bikes that are particularly fast or heavy may have vented discs.

Early disc brakes (such as on the early Honda fours and the Norton Commando) sited the calipers on top of the disc, ahead of the fork slider. Although this gave the brake pads better cooling, it is now almost universal practice to site the caliper behind the slider (to reduce the angular momentum of the fork assembly). Rear disc calipers may be mounted above (e.g. BMW R1100S) or below (e.g. Yamaha TRX850) the swinging arm: a low mount is marginally better for CG purposes, while an upper siting keeps the caliper cleaner and better-protected from road obstacles.

A modern development, particularly on inverted ("USD") forks is the radially mounted caliper. Although these are fashionable, there is no evidence that they improve braking performance, nor do they add to the stiffness of the fork. (Lacking the option of a fork brace, USD forks may be best stiffened by an oversize front axle.

If I remember correctly, my first dual front disc bike was my new 1981 Yamaha XS 1100. The most powerful dual discs were on my new 2001 900SS Ducati, where one finger would quickly stop the bike, where a person had to be careful as there was no ABS:biggrin:

Sam:coffeescreen:
 

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A modern development, particularly on inverted ("USD") forks is the radially mounted caliper. Although these are fashionable, there is no evidence that they improve braking performance, nor do they add to the stiffness of the fork. (Lacking the option of a fork brace, USD forks may be best stiffened by an oversize front axle.
Actually, there is an advantage to radial mounting. Due to how radial mounting mounts, it is relatively easy to go with a larger front pair of disks, as long as you use appropriate spacers, or calipers with the proper spacing. Non-radial mounted calipers are pretty much fixed in position, not allowing for moving to a larger set of disks.
 

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The Goldwing had dual front disks from day 1. The first prototype Goldwing was made in '74. First production units in '75.
BMW offered dual front disks on the R90/S in '74.
 
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