Rick...sounds like you and I have been on a parallel path with these Phat bikes
. I am sure you noticed that on the black one I did the exact same thing you did and laced a Nexus 7 to the original offest wheel. It is close but it works great.
For the Yellow one, I had a 100mm rim. There was no way I could see to fit a Nexus 7 on it, so I opted for the Nexus 3 speed with an offset sprocket. The 100mm rim I had is stock with center spoke holes (not offset like the stock 80mm rim). Here was my initial quick look (no measurements) to see if it would work:
Without measuring it, it looked like it would work. Laced it up and compared it to the 80mm:
At this point it didn't look like the chain would clear even with the offset sprocket.
So what I did was took the retaining clip off the sprocket and moved the sprocket as far away from the hub as I could just to see if the chain would clear if I had more offset in the sprocket. It actually would...BARELY! So...it was late and I just wanted to see if I could get it to work. I put a spacer and another sprocket between the offset sprocket and hub, I put a bearing race and bearings (that I had sitting around from a nexus 3 speed I blew up in the past), tinkered around with spacers, washers and my mic tool and got everything working. What I had to do is put the bearing races in hollow of the offset sprocket and grind and mic and grind and mic until the clearances were about .5mm so everything would spin freely. I should have taken pictures of this part, but it was late in the evening and I just wanted to get it done. Probably not the very best way to do it, but it works, is safe, rolls smoothly, looks pretty good and most importantly I have 100mm in the back!
I think in a perfect world, if I had a Surly 100mm rim with offset spoke holes and about a 18mm-20mm offset rear sprocket, that is all I would need to get it to work (I am in the process of sourcing these parts to see if I can do the same for the black bike). I will keep you posted. Hope this helps! Shoot up some pics of your Phat...would love to see it!
If I can't find the offset rear sprocket I need, I have a 24x4.25 tire that I may test fit on the black bikes stock rim to see if it gives me the look I am after. I wonder what the 4.25" wide tire would look like on the yellow one with the 100mm rim :mrgreen: ...never ends