Not sure quite how that's relevant but the main difference is that building your own PC lets you get something faster, better quality for less money. Building your own bike costs a hell of a lot more than buying a spec bike, before you even factor in the cost of tools and labour. And what you end up with is generally a pretty sideways move, not an obvious jump in quality.
PermaBanned, its relevant because chaparral the o.p is getting caught up in the conceptual ideas of others and not allowing himself to create his own perfect bike, he has some ideas in his mind of what he wants and doesn't want and is trying to match his idea to an existing concept . . . the point I am making is that the way one specs and builds a computer for their personal use is exactly the same as the way one specs and builds a cycle for their personal use.
I don't agree with you when you say " Building your own bike costs a hell of a lot more than buying a spec bike, before you even factor in the cost of tools and labour". What exactly do you mean by a "spec bike" and why are you assuming a custom cycle costs a "hell of a lot more"?
A custom "machine" doesn't have to cost more? this depends on how good you are at sourcing components surely?. If you are suggesting an economy-of-scales thing where the cycle manufacturer is able to sell the whole machine cheaper because they are making bulk orders of the parts then you have a point but to some extent this discount gets wiped out by a branding fee. I did all the research myself (thank you google) and paid a friendly wrench £60 to do all the tool work (bottom bracket, headset) and I did the rest, it's not expensive at all?
Have you ever built your own cycle PermaBanned because when you say " you end up with is generally a pretty sideways move, not an obvious jump in quality" I'm wondering if this is a theory of yours or based on actual experience?
If chaparral can research, spec and build a computer for his personal use then the same applies for a cycle for his personal use. If his end result is anything like my end result I would say its anything but a sideways move, how can it be? it's a "custom" cycle, custom trumps "spec" all day every day. He just needs to understand the different parts so he can choose whats right for himself.
You should try it yourself, I don't see any difference between a custom PC and a custom cycle and I'm saying to chaparral he can "invent" his own bike that is exactly what he wants and he doesn't have to subscribe to the conceptual ideas of others.
From the little he has said I think the "flat bar road bike" concept is what he is after, nice steel frame, large 700c wheels, not sure of his gearing requirements