The SL 4 came with the off-brand bb, looks like the flash has a Shimano. I replaced with Shimano, so I treated it like an upgrade. When I told the shop I bought the bike from about the problem, they said they have had issues with Cannondale "forgetting" to grease bottom brackets. If you have eliminated other possibilities (pedals, cleats, handlebars, seat post) it might be worth pulling the bottom bracket to inspect and re-grease. I ignored the noise, and that is probably why I had to completely replace the part.