they also don't have the diseconomies of scale
All the experience of history says otherwise. The big companies have economy of scale, and any small ones who make anything people actually want to buy either have to grow or get taken over by the big ones.
who wants to be selling £250 bikes
That's what killed off the UK motorbike industry, along with most other consumer goods. UK manufacturers sneered at the "cheap rubbish" from Japan, and scoffed that they don't need to compete because "we make superbikes", then they found that the Japanese could make superbikes as well. The issue is not who wants to sell £250 bikes, it's who wants to buy them. Cyclists like us are only a tiny fraction of the market. There are even people who will chuck a bike out and buy new just because it needs a new tyre or has a puncture.
Look at small-volume up-market supercars for example, they're full of components poached off mass produced cars because development and the tooling to make them is expensive, and they don't have the volume to amortise those fixed costs. They use fibreglass bodies for the same reason: the fixed costs are lower than for the press tools to make steel. I recall seeing a motoring journo cooing over the expense and luxury of a turned aluminium gear knob on a supercar. Not having any understanding of engineering, he couldn't see that it had an aluminium gear knob for exactly the same reason that a Ford Fiesta has a plastic one:
it's cheaper! The fixed cost of tooling to make injection moulded plastic components is prohibitively expensive without sufficient quantity to amortise the cost. (Conversely, turning every one on a lathe is too expensive if you're making millions.)
Any bike shop who wants to "make" bikes is in the same position. They're not
making them at all, they're just assembling parts made by the big companies like Shimano, and I can assure you that Shimano are not going to give them the same price as they offer to a big customer who's buying thousands or millions of times the quantity.
Britain will continue to import labour and export jobs until the wealth difference that's driving the process reduces (unless Brits decide they're willing to work for the same wages as someone in a Far Eastern sweatshop). The UK had its chance to be more competitive decades ago by investing in automation to improve productivity, but we chose not to. Now it's too late, and everyone else has left us behind, so we try to rationalise it with nonsense phrases like
"post-industrial economy".
The economic superpowers of the next century will be the Asians.
