I'm using an IGH with semi-horizontal dropouts. The ratio I have now is not working well. As it is, I'm at the very back of the dropouts and can't really maintain adequate chain tension. If I take a link out, the non-turn washers stick out the front of the dropouts.

So, question is: the axle-crank distance will change by how much for each incremental increase in chainring size? If it matters, I'm using a ~38 right now.