gear ratio question
My bike has a 48/38/28 crankset and an 11-32 casette. Why is there so much overlap between the cranset steps? For example, the tallest gear (11) when riding in the 38 gives me a mechanical advantage of .289, which would fall between the second (13 -- .271) and third (15 -- .313) tallest gears riding in the 48.
If you are going to have a triple crankset, why not space them out more? If they went with 53/38/23, for example, the range would be 10 teeth larger and you would still cover the entire range, with considerable overlap.
If the answer is, you can do it that way, what should it cost to have my LBS make the conversion? I don't need high-performance parts, but I don't want total junk, either.
Thanks for any input.