Yeah, I wasn't conditioned to carry the bike up the stairs after a ride. I was very naive about it, and never even thought about the strain on my body until it was too late. Because I'm slim and I've spent my whole life playing all sorts of sports I figured I was fit enough to just get on the bike and go. I started with 15 mile rides! (Just to point out I wasn't riding every day. Usually did two or three rides a week) I'd ache afterwards but would heal well and be ready for another ride several days later. I adapted to that quite well over the following weeks, but I upped the mileage way too soon, doing tough 30 to 40 mile rides not long after the 15 miler. Then I'd notice my legs would start to ache bad during the hilly sections of these rides, and my average speed had dropped, but I didn't read too much into it. I just pressed on. My quads would ache on these rides, but I'd get home and lug the bike upstairs each time.

Like you say, I'll go very easy for atleast the rest of this year. I'll walk more and do low resistance cycling, and hope this improves with a bit of time.