"Rockers was a term originally applied in a derogatory manner to British motorcycle-riding youths in the 1960s, but was later adopted by those same youths.
Rockers became defined as the antitheses of their scooter-riding contemporaries, the mods. Before this time, young motorcyclists had not been grouped together and labelled in such a manner. Mods and Rockers attracted attention in 1964 because of sensationalistic media coverage of fights between the two groups. Mods and rockers became known for Bank Holiday clashes in the southern English holiday resorts of Clacton, Margate and Brighton."
Some Brilliant history from cafebiker.com
"A Rocker was a motorcyclist first and foremost not a mere fashion or youth music trend. Theirs was a style born out of necessity and practicality and they will generally be seen riding their motorcycles wearing a classic open face style of helmet and aviator goggles, especially the "pudding-basin" short style of helmet such as those still made by Davida Helmets. Davida has been providing helmets for 30 years. They have a worldwide reputation for the quietest, most comfortable, and well made helmets available.
These cafe racers or Rockers wore simple 501 or 505 Levis in blue, dark blue or black, leather trousers were also quite popular. These trousers and jeans were worn with either tall motorcycle riding boots, made by Lewis Leathers, engineer boots or Creepers, as is still the custom for modern-day Rockers. T-shirts and Daddy-O styled shirts were worn under heavily decorated leather motorcycle jackets, adorned with studs, patches, pins and usually an ESSO Petroleum 'gas man' trinket hung somewhere from the jacket. Also quite visible and popular was a patch declaring membership to the 59 Club of England, a church-based, youth organization that later formed into a genuine cafe racer club with members all over the world. Last but not least, while out riding, Rockers would usually wear white-silk scarfs to protect from the cold and cover their mouths while in inclement weather."
What Makes a Bike a Cafe Racer?
Rocker bikes are only "stock" when brand new. Customizing at a rather primitive level is the absolute rule. First to go are the standard handlebars, which are replaces by clip-ons. Racing type tank and seat are next. Then come modifications to the exhaust system, plus new paint and other minor decorating. The rockers strive for a "racer" image and so rarely hang superfluous goodies all over the machine. Neither do they do much about brake or engine modifications. The aim is therefore to get the best possible performance from essentially stock engines. Since individuality is highly regarded, there were many specials, such as Tibsas, Vinors, and Tritons.
The unannounced but widely understood ritual of initiation into this brotherhood, we learned, is "doin the ton." As one young rider told us, "You have to do it once. Of course you don't ride around at 100mph all the time, but its good to know you've done it, to know you bike can do it or once did it." Ad they don't do the ton on a racecourse on a flat stretch of country road. Likely as not they do it on the North Circular Road, or the Watford By-pass or the M1(one of Britain's few limited access expressways). They don't do the ton in broad daylight when there's no traffic and the pavement is dry. Likely as not they do it at night, when challenged to burn-off (or burn out). The air will be damp and the high beam won't be good for more than 60 mph and there will be trucks and cars of all sizes on the road. And that, mate, is when you do the ton. There has to be a story in it, for it will be told by a rider and his chums many times over. You have to make it good.
Beside the nightly round on the cafe circuit, rockers occasionally organize what they call a weekend "burn up." This takes the form of a fast cross-country ride to some point in the north of England or to Wales of Scotland. Within sixty miles of London lie the Brighton resort area and the Snetterton and Brands Hatch racecourses. These are too close for an all out burn up, and more appropriate destination is Liverpool or Manchester or even Edinburgh(470 miles). Trips take two days, possibly with a layover at a friendly club or possibly straight through. A burn up is a major adventure for the rocker. Like doing the ton, it gets plenty of retelling (and possibly embellishment) in the weeks that follow."