My personal favorite for comfort is pk shell earbuds. IMO the RX1 is still too large depth wise for perfect comfort.
Pk or Qian/monk lite type shell comes the closest to perfect comfort.
Actually apple earpods are really comfortable too for that use, did you consider just buying some earpods? Although I know some don't find them as comfortable as others...
Anyway try the diy pk2 sr2 on aliexpress from chittys store.
@jogawag may get you a link to the best version (one vent or two). My aliexpress links never work for people.
Although i gotta say. The rx1 had a sturdy cable and Jack. Where on the cable did it break on you exactly?