Seriously thinking about buying the BB9 non-suspension model. I have a set of 29er Bontrager SS wheels that I want to put in so I can use wider tires. I also want to go SS. But how wide can I go? I'm looking at Michelin City 700x40c. The BB models come with Schwalbe Kojak tires 700x28c. The bike shops I went to don't have the BB9 in my size for me to check out. I was able to look at a BB1, but I couldn't visualize how big of a tire the rear will accept without rubbing against the seat stays or behind the bottom bracket.

Also, anyone know if the base BB with the 1 1/8 headset will accept any regular headset, such as the FSA Orbit MX? Pictures seem to show that the BB has an internal headset. Not sure exactly what that means.