Got to say Simplex's choice on ring sizes is really annoying.
Simplex Competition double chainwheel
.
116 BCD
Outer 48 - 52
Inner 45 - 48
.
Simplex Tourist double chainwheel
.
50.4 BCD
Outer 44, 46, 48, 50
Inner 28, 30, 32, 36, 40
.
1953 Simplex catalogue
