Hey guys, I am a formerly in shape biker that needs a new cassette. Back when I was in shape, I changed my cassette to an 11-25. Well now I would like to climb some hills again, and until I trim the extra tire that has formed around my waist hills are not going to happen. Can someone tell me what the largest cassette I can move up to with a Shimano 10sp rear derailleur? The bike came with a 12-28 Tiagra cassette, but I would like to move up to a 30 or 32 (if one exists). Thanks for the help.