Thanks for all the help! The cassette is 11-32 and since there's only one ring on the front that comes out to 21t. The only issue is the size of the big cog which is 32, which is a problem for the parallelogram and not the cage length. My road bike has an Ultegra RD. The cog is not nearly as large as 32, but when I observe the motion of it, it would easily facilitate a 32 cog. If I get a Shimano 105, I may have to adjust it so the upper pulley will fit over the 32 cog, and as a result there may be more of a gap between the pully and the 11 cog, but the chain tension will be great. I'm also not concerned with perfection in the highest gears since I rarely get up that far. I think a Shimano 105 SS will work fine, so I'm going to buy one. If it doesn't I'll just have to buy something else. Now to choose where to buy!