Originally Posted by
oldpedalpusher
I took a look at the Nexus 3 speed parts and your rear sprocket ~appears~ to be similar to a Sturmey Archer 3 speed cog which is made in larger sizes for better hill climbing.
Yep, the Shimano 3s, SRAM/Sachs 3s and any Sturmey 3 one is likely to run into all use the same sprocket format, along with the Shimano 4, 7 and 8-speeds, SRAM 5 and 7 speeds and Sturmey 4, 5 and 7 speeds. Many coaster brake hubs use this same cog.
Decades ago Shimano based their cassette cog design on this format, and useful cogs for IGHs can be homemade from cassette cogs.
These IGH cogs are available in 13T to 23T sizes, and for 3/32 and 1/8 chain. Various dishes are made to adjust the chainline.
tcs