I have a Shimano bleed funnel which I've used on various MTB levers; I just bought one and it worked, I wasn't aware that there were different ones.
Whilst browsing the Merlin site, I came across a (silly expensive) Shimano bleed kit which contains 2 funnels, one with an M5 thread for mountain bikes, and a second with an M7 thread for road brakes - is this what I'll need for the GRX brakes?
One of these and the funnel that you already have
https://www.sjscycles.co.uk/gear-spares/shimano-duraace-str9120-funnel-adapter-oring-y0c698050/
Just need the adaptor and what ever you already use.
Tip: if your bars are very flared tip the bike so cup is horizontal, bleeding is much easier. Flare tips the brifters on an angle and traps the last if the air
This is the one time where Amazon is your friend. I've used this for multiple shimano brake sets and it's excellent and has every adapter I have needed
Thanks.
Epic have the adapters too.
drop me your adress, and i'll send you one, got a few loitering in the workshop.
Wow, that's really kind, thank you.