Thanks for your reply. I measured the frame for the bottom bracket, and it is 68 mm. Maybe it's not a "real" mountain bike frame? It had a real low price point. Also, the BB-UN26 68 x 113 is the one Shimano recommends for my new Alivio crankset, and Alivio is a mountain bike component line. Is it possible I did something wrong in installing the bottom bracket? I used a torque wrench to get it right. And I don't see how I could have gotten it too far in on one side or not far enough in on the other. But is that possible? Also, if the same bottom bracket shifts to the left 1.5 mm, that would increase the inequality in spacing between the crank arms and chain stays by that much also--to 21.5 mm on the left and 16 mm on the right. Correct? Please let me know if anything I'm saying doesn't make sense.