I just bought a Dahon Formula S18 with the plan to swap out the cassette to get lower gears (I live and work in hilly area - more concerned with climbing hills than beating speed records). It's being delivered tomorrow. I believe the largest cog has 27 teeth [EDIT - it has 25. The cassette is 11-25]. I was told by the salesman I will be able to swap it out for either an 11-30 or 11-32 cassette. However, I just read on Shimano's website that the largest cog this particular rear derailleur can handle is 27 teeth. Now I'm wondering what my options are. Are Shimano's specs conservative and can I likely get away with going up to 30t? Without negatively affecting performance? If not, what about changing out the small chainring up front for a slightly smaller one? How can I figure out if that would work (i.e. could the front derailleur handle it?)? The front chainrings are 56t/46t. Any ideas/suggestions?