Easier gears on a RC500
Shimano until recently has kept a strict distinction between the Road and MTB groupsets. For commuting or loaded riding with drop bars, the groups offered on the (consumer grade!) RC500 is Sora, with a compact road double (50/34).
Shimano offers a tiagra-series 48t outer ring in 4-bolt 110mm asymmetric BCD. Additionally, Specialties TA or AliExpress sellers offer a 33t inner ring. 48/33t is a nice step down, when paired with a 34 casette.
This combination does not offer enough clearance between the rings. In the small ring, the chain catches on the guides the outer ring uses to accelerate shifting. I added 0.5mm washers, of size 10mm ID – 16mm OD on the barrel nuts of the outer ring.
This spaces out the rings enough for the 10 speed chain to clear. I believe a 9 speed chain would still interfere. Shifting is fast and easy, and the extra low range in the big ring is really useful.
