What are the differences between new Nexus 7 speed hub (SG-C3001-7), versus old (SG-C3000-7)? From the outside shells seems to be different, but are there more important changes inside that influence durability or efficiency?
I don't know what the actual changes are, but the newer C3001 hubs are now listed by Shimano as being e-bike approved, which implies a ratcheting/drive mechanism that's more suited to the higher force inputs of a mid-drive assist system.