I have a couple of them but need a QR. Is there an universal 20mm-9mm reductor? Can't see a reason why not. Anybody knows? Thanks.

Don't think so. Hope wheels convert back to QR, not sure about any others. Pro2 and Bulb have different adaptors so probably no such thing as a universal converter.

Makes me wonder why not? They are probable the same width, same internal diameter of the hub 20mm, so a tube with 20/9mm diameters would suffice. Or wouldn't it?

I guess the bearings could be a different outside diameter, or could be a different spacing across the hub (i.e. the "hulahoops" on the outside of the 20mm hub could be different width).

The Hope adaptors aren't interchangeable, can't remember which way round I tried it but it didn't work.

But all 20mm hubs take the same bolt-thru axle. I'm thinking if one can machine a similar axle but with ends to fit a QR fork.

old is different.

Where's the dilemma?

20mm fits 110mm fork spacing, QR is 100mm

GW, now I know why, thanks.