If you're 6'1", a 52cm frame is going to be waaay too small for you; you should be riding at least a 58. The tricky bit with Surly is that they measure center-to-TOP, not center-to-center; ergo, their 54cm frames are actually about 52.5. I normally ride a 54 or 55, depending on the geometry, and a 56cm LHT still fits me pretty well.