Figured out my backpack was the reason my back hurt every ride home
For about 6 weeks my lower back ached by the time I hit my block in Chicago, and I kept blaming my saddle height. Then a guy at the bike rack at work watched me swing my loaded backpack on one shoulder and said "that bag is dragging you sideways the whole ride." He was totally correct, all my tools and laptop sat off to one side so I was leaning to balance it without even noticing. Moved the heavy stuff to the middle and strapped it down tight, and the ache faded in about a week. Anyone else fix a nagging riding problem by changing their bag setup instead of the bike?