My beloved three-speed bicycle had three problems, one after the other.
First, the rear tire went flat.
After I fixed that, the chain would skip gears (or at least it felt that way).
After I fixed that, something was slipping, such that when I pedaled hard, some of the effort was lost to just making the rear gear spin. This made for mushy pedaling.
I can hear the clamoring begin to rise: “Throw the old thing away already! Get a new one!”
Now, now… this is my legacy system and it meets my requirements. :) I just want to write down what I did for the latter two fixes, since I think I’ve experienced these same issues in the past and forgot:
Skipping Gears Fix
Why was the chain skipping gears? I never could see it happening, but I do know that increasing the tension of the chain (by loosening the rear axle and moving it backward) fixed that issue.
Mushy Pedaling Fix
Why was the pedaling mushy? When I fixed the slipping gears problem, I moved the serrated washers (these might give the idea) on the rear axle from the inner side of the metal frame to the outer side. I don’t remember why I did this, but it seems to have enabled the mushy slippage. I moved the serrated washers back to the inner side of the frame (working to maintain chain tension!) and the mushiness evaporated.
No unit tests… a lot of moving parts… you start to get scared to change anything… hmm!