Originally Posted by
flink
plus, I figure there's a fair amount of redundancy within those gears as well. not like I've ever sat down and done the math but out of twenty one gears, once you factor in all the duplicate combinations I wonder how many gears you're actually left with
Gear Calculator
Plug your numbers in for cassette and chainring teeth count. Go to "Speed over RPM Range" and check the sort box. You can see where your different ratios fall in relation to each other.