So, I've always been a Campy guy, but I'm pretty familiar with Shimano stuff, as it's on almost every bike in the shop where I work. I got a little confused with some of the compatibility issues when the 7900 and 6700 stuff came out, but I thought I got it all figured out. However, I ran into an issue tonight. I have a cross bike set up with SRAM Force, but with a 6600 cassette and a 7800 chain. I'm building a new road bike and borrowing some of the components from my cross bike, namely, the wheels. I went to put on my new cassette, which is an 11-25 6700 cassette. The old one is a 12-27 6600 cassette. I'm sliding the cogs of the new cassette on to the freehub body, and I have like 3 left to go, and I think to myself, 'there's going to be space left over.' Sure enough, I slide the 11t cog on, and there's space for a whole other cog. We're not talking slack that would be taken up by the 1mm space that Shimano provides, we're talking major gap here. What's the deal? Am I overlooking something?