Enve Innerdrive Campy N3W freehub head scratcher

[Julien]

I’m having an interesting time installing a SR 12 cassette on a N3W freehub for a new-to-me set of Enve 4.5 with the freshly released inner drive hubs.

My 13t cog is sitting flush with the outer edge of the freehub body. I have no room for the 12t cog to go in and the lock ring (which should support the 11t) has no purchase at all and won’t make contact with the thread inside the FH body.

Am I missing something obvious?

The cassette is going all the way in, the big cogs cluster is all the way down, I’ve triple checked that I have the right FH body. I have used the cassette exactly as it is on another set of wheels and never had any issue.

The cassette width from big to small cog is roughly 1 1/2. The freehub body is about 1/4 narrower than that. This has to be a plug and play thing but I can’t see what I’m doing wrong!