Blown Up Cog
Here is the EAI cog that blew up while riding my Bianchi Pista. I think it cracked when I braked hard, then literally blew to pieces later in the ride when I went to accelerate from a stop. It was a 16 tooth, 3/32nds steel cog on a Campagnolo Pista hub.
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Footnote: EAI replaced the cog under warranty and threw in something to boot. I sent the cog parts I located to EAI for testing. Great customer service by EAI.