Rode 8 miles to the office with my rear brake rubbing and only figured it out at the bike rack
So I've been patting myself on the back for months about how strong my legs were getting on the ride into work, grinding up the one hill on my route in a harder gear than I used to. Last Tuesday I get to the office and a guy locking up next to me goes 'your back wheel barely spins, buddy' and gives it a flick. The wheel stopped in about a second. Turns out my rear brake pad had been dragging for who knows how long, maybe since I adjusted it back in March, and I was basically doing leg day twice a day without knowing it. I loosened the pad, spun the wheel, and it coasted forever, and this morning the same hill felt like nothing. Now I'm wondering how much faster my whole ride could've been this entire time. Anyone else ever discover their 'fitness gains' were just a mechanical problem?
A dragging brake for months would've cooked your legs way more than you think, so I'd bet the fitness is real and the speed is just a bonus now. Half the people I ride with have some rub they never notice, and they still get stronger. Fixing it probably means you were training harder than you meant to, which isn't a bad thing.