A Frame of Two Halves

I'm pretty sure that the hard cases are about £400, don't think that they sell that many, hence the price. Even the Ritchey softcases are around £200?

That’s mental, there can only be a couple quids worth of plastic sheet and about 10mins on a vacuum former to making one. Even making the mould would be pretty easy since it’s just a cuboid shape.

Suitcases are too small. Don't think it is wide enough for the wheels, which is generally the limiting factor of suitcases.
You can easily find rectangular suitcases, but not tall & wide enough to hold 700c wheels.
Needs to be at least 26 inches wide.

A 1690 Pelicase is “L784xW660xD394“ ss o should be large enough.

£400 odd new but there’s one on eBay at just over a ton just now.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F323945815213

Even if that’s not quite right (it’s probably a lot deeper than you need and probably too heavy) then I think it puts into perspective how overpriced the bike specific ones are because the bike ones I’ve seen look weedy as hell compared to a peli.

The Pelis are monsters, that’s the internal size, not the external and weighs around 16kg.

Ritchey bag is 21.6x67.3x78.7, so makes the package about 16kg with a bike + tools, bottles, shoes, etc that you might want to add.

You could make a custom flight case or buy them in the appropriate size potentially.

Some thing like this might be fit for purpose?

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F173854535374