Originally Posted by
Lombard
Cassettes cogs are either steel or Ti, not aluminum alloy. Aluminum alloy would wear out super quickly against a steel chain. .
You are correct, but there have been cassette/ freewheel cogs that have used aluminum alloy big cogs to save weight. The larger the big cog the slower it wears out considering how seldom it is used. Aluminum alloy cassette/ cogs have often been used over the years