Proper noob moment this morning. Last night I notice a scratch on my rim baking surface, I was concerned, but also sleepy, so this morning I inspect it further,it goes half way around my rim, "oh sh*t" im thinking. Commute to work, then have a good old look in the office. "Even worse goes all the way around" (this was obtained by removing a sticker covering the "crack"), sure fire failure I thought, was not impressed, there goes the aero helmet funds on a rim and rebuild, OR NOT! Long story short, Its the damn join when there rim has been manufacture, in conclusion, I am an arse, lol!