R&M Birdy are already expensive, if the customer needs to rebuild a rear heel with an XDR hub (which aren't cheap), it will become quite expensive.
Did you try to order a new Sunrace cassette from a R&M dealer ?
I tried to order some parts from R&M dealers in Belgium and The Netherlands and for spare parts, R&M asks for the R&M frame number of the Birdy... which I do not have since I have a Pacific Cycles titanium Birdy (I was looking for a 32 spokes Birdy disc front hub, I could only find the Hubsmith Birdy disc front hub which is 24 or 28 spokes).
Last edited by Jipe; 01-11-21 at 10:56 AM.