here's my situation:
- first bike build
- chinese carbon frame, brand new
- sram pc-1070 11-28, 10 sp
- sram force rear derailleur, 10 sp, medium cage, brand new
- chain not yet installed
- cable routed, but not yet connected to derailleur
- derailleur hanger looks like
this one
- derailleur hanger alignment checked with with park tool DAG-2 alignment guage
- sram recommended derailleur hanger length (L) is 26 - 28 mm
- derailleur hanger length as measured on my frame is 27 mm
- confirmed the b-adjust washer tab is clear of the rear derailleur dropout tab
- the closest i can get the top pulley to the cassette cogs is 9-10 mm, this is with the b-adjust screw COMPLETELY REMOVED
- inserting the b-adjust screw just makes the gap even larger
- gap remains as i push the derailleur in with my thumb along the full range of cogs
- reference picture with a 6 mm hex for scale
at first i thought the hanger was too long, but it measures within recommended range. checked the hanger alignment, can't imagine RD is bent since it's new out of the box, some googling indicates medium cage should work with 11-28t cassette... i'm not sure what else to check. any suggestions?