Originally Posted by striegel
Wow! I have no idea how that can happen. Every sprocket on the original 5-speed freewheel of my 1973 Paris Sport is still in great shape after more than ten thousand miles.
I have about 28,000 miles on my 1978 Raleigh Super Course and virtually all of that is post-1986 on a six speed rear cluster.
If you ride with the chain being stretched for a while, it will wear the smaller cogs to the point where the chain can jump under high torque conditions (like pounding up a steep hill in a tall gear, standing up). Usually you will only notice this once you put a new chain on worn cogs.
I have had to change the smallest cog twice now, so once every 9000 miles or so. As I say, you usually will notice the jumping of gears when you fit a new chain. Chains should be changed every couple of years, if you ride say 1500 miles a year, as a rule, to avoid this.
If you have an original chain on a 10,000 mile bike, it is mega-stretched and as soon as you put a new one on, it will skip on the smaller cogs.
The chain is meticulously clean at all times.
I really should invest in a chain gauge.....