I bought a takeoff wheelset off the 'bay, and it came with a brand new 105 cassette and 23mm Bontrager tires. It's useless to me (on the road) where I live because it's a 12-30, but I thought I'd throw it on a spare wheel for the trainer. I should have tried it right away but I took it off the hub before I thought of it. Anyway, does anyone know if a 30 tooth cog will function in a 6700 Ultegra derailleur? I know Shimano says it's not compatible but I was wondering if anyone had tried it. I also know I'll never need that cog for a trainer wheel; I'm more curious than anything.