Converting Surly new hubs from 130mm to 120mm
No, this conversion isn't possible. The 130 version has a different shell than the 120. The flanges are further apart. That's the good way for them to have done it, because if they had used the same flange spacing throughout, that's wasting lateral strength on everything but the 120. If you look at your hub you'll see that there's not really anything you can take out to get the OLD down very much.