Originally Posted by aadhils
The point is chain wear. The chain is worn out along with the chainrings, and they conform to each others shape. If you change the chain, then the new chain wears out faster to to conform to the already worn out chainring.
So unless the cogs are pretty new, I would'nt change the chain without changing the cogs and chainrings. btw, most chains and chainrings of similar sizes are interchangeable.
He said he "just recently bought" the bike. His chainrings aren't worn.
NoNafs: Can you tell us what markings are on the old crankset (is it 2200?) and what series of Ultegra stuff you bought (ie, 9-speed or 10-speed)?
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