I am selling my first road bike. Unfortunately I had to guess the year of purchase, could have been 1997 or 1999. It stood unused in my parents' cellar for many years. In 2021 it was completely overhauled by the bike dealer: Inspection, new chain, new cassette (Shimano 8-speed, 13-23), new tires (Conti Ultre Sport 2) ,new shoes, new brake pads, new handlebar tape. After that I rode it exactly once, everything was tiptop. Then the bike sat unused in my garage again. During a test ride yesterday, I noticed that you can't currently shift from the big to the small gear, for whatever reason. Apart ...