My worst bike was my first, an all steel (including rims) BSA...
I took over my Dad's Raleigh All-Steel Bicycle as my first adult bike, when I outgrew my Norman of England child's bike. He'd had the Raleigh since he was a teenager. I really rather liked it. Once you got it moving, it went quite well.
I remember stripping and reassembling the SA 3-speed hub, looking for a reason why the gears slipped (it was, after all, 25+ years old by then). I didn't know enough to find the fault, and had to take the wheel to the LBS, who diagnosed and replaced a worn clutch.
I also spent some time replacing parts on the roller brakes, which had worn pivots, but never got them working well. In the end, a physics teacher at school, who happened to be a friend of Dad's, saw me braking at a junction with my feet on the ground, and suggested to him that a new bike was due.
A second-hand Falcon was found. I did my first club ride on that, and never looked back (except when turning, of course).