I'm having to go through several older bikes I like and replace freewheels that have worn. I'm thinking about going with a 7 speed Shimano MegaRange-type (which must be ordered) unless I'm changing the whole wheel. I am having a tough time making up my mind on what to use with this one, but I'm starting to lean toward an 8 speed SRAM freehub. Either way, I'm wanting something that will stay in production until the futuristic glider bikes become viable (which may be awhile). Either way, I'm wanting insane range (about 40 to 10 teeth sounds right) but don't care so much about each step. I still want each step as even as possible to the others. What would be best for my US Dollar?