Fred is a common term of disapprobation used by roadies. It has two meanings, which can ame it a bit confusing.
1. The original meaning: Someone [usually a man] who rides a bike not for sport, fitness, commuting or pleasure, but as a kind of anti-capitalist, environmental statement. Roughly, he's a hippie on two wheels -- wears jeans and sandals, rides a beat-up, rusted mid-70s utility bike [often a woman's frame] less out of necessity than principal. Freds are often university professors, community radio volunteers or health food store owners. You see them a lot at critical mass protests. They're not commuters because they don't usually go very far and tend to live and work in the same neighbourhood. They do little to maintain their bikes and think that sport or fitness cyclists are capitalist poseurs. Fred from Fred Flintstone [because they're cave men], the female is Wilma.
2. A sometimes more common definition: A poseur. The guy with a lot more money than brains. This is the guy who spends $6,000 on the latest high-tech bike, $1,000 on matching team strip, $400 on the coolest shoes and doesn't know how to fix a flat. These Freds will often go for 20-40 km ride a couple of times a week. They know nothing about ride etiquette or the lore and traditions of the cycling community. You can call them Fred and they'll say "no, my name's Jerry [or whatever]." Some of them have never actually seen an allen key and wouldn't know what to do with one if they saw it. They are often men in their 40s with a great deal of disposable income. Wilmas of this type are, sor some reason, exceedingly rare.
I don't actually LIKE the term "Fred," and I find it a little velosnobbish. I do have some respect for type-1 riders, though I have come across a couple who are willfull and sanctimonious and whom I would generally class as "freds" because I don't like them personally. And there is a bike shop near me that specializes in used Fred bikes that I [and others] call the Fred shop.
On the other hand, I have been known to refer to the type-2 guys as Freds wuite liberally -- not because they're so bad or because they like to burn money, but because I find some of them to be dangerous and irritating riders. [I'll relate the Festina Boy story some time.]