Sorry for the late response, but I really appreciate the advise. I'm starting from near-zero knowledge on what makes a "Schwinn" 1 3/8 different from all the others. The 597mm do appear to have next to nothing in the way of options. I have the 597's, and until I get things torn down a little further, I'll keep looking in that vein. If I go with a new wheel set, 590's are my avenue.