Got my new bike from France, and I just want to get all this done and ride. I don’t have olives, barbs or the yellow hose clamp. Can I get away without olives and barbs, just undo, swap and hope for the best?
Possibly bleed, but I would like to avoid that.

These ones.

If the hoses are the right length, then a very careful swap may even mean no bleeding required.

Length wise they are fine.

Never needed to bleed when I’ve swapped or shortened them.

I do this a lot and never need to bleed them. I´m reasonably careful to keep the reservoirs level and keep the hoses out for as little time as possible and it´s fine. I find that on bikes where I´m swapping the hoses regularly they eventually need bled but you get the bleed kit for a couple of quid or something so it´s not hard!

IME it’ll work without a bleed 99% of the time.

Make sure you don’t squeeze the levers with the hoses loose 🙂

Loosen them both then pull the hoses out, being careful to keep them from dropping.

Make sure they’re pressed well home before doing the nuts up again.

You should really change the olives too as they deform on tightening, but in reality you’ll probably get away with it.

Just keep an eye on them for weeping where the hoses enter the lever.

I followed this when I did mine. Worked Ok but did have to bleed eventually to get them spot on again.

http://www.epicbleedsolutions.com/blog/shorten-shimano-hoses-without-bleeding/

A had a helper, we undid and swapped. All went together fine, the rear needed a pump but is holding firm now. Thanks all, I just needed the reassurance to go and do it.

Done it a couple of times using the epic bleed solutions guide as linked by “Survivor” above, no bleeding required, but that’s simple too.