Good stuff like this never happens

I'm not much of a mechanic. I can change tires, patch flats, put on cassettes, put on a new chain, but beyond that most bike maintenance is over my head. 

I have a set of 650B wheels and a set of 700C wheels. I recently purchased new derailer to handle a larger that I had installed at a bike shop. I had hoped to be able to swap the wheels back-and-forth painlessly. Alas, when I had the derailer adjusted for the 650B wheels the 700C wheels shifted really badly. They wouldn't go into the highest or lowest sprockets..

I figured it was due to a variation in the hubs or cassettes and that I would have to adjust the cable and put a spacer behind one of the cassettes, and generally do things that would be way over my head. 

I avoided it for as long as I could. With great reluctance I decided today would be the day would work on making both wheels shift equally well. I was not expecting a good outcome. 

 But when I got the bike on the stand I realized the shifter cable tension was just fine. I thought perhaps the derailer limiter needed to be adjusted; perhaps that's what was stopping me from shifting to the largest and smallest sprockets. 

Three quarters of a turn later on the high end and half a turn on the low end of the limiter screws and my 700C wheels now shift perfectly. It was so easy I am still expecting to discover something horrible. But right now I'm happy guy with a well-shifting bike trip