The bike is a 08 Look 566 with 175mm crank. I guess I should have done some more homework on the gearing. The bike came with 12-25 which at that time, I could not use. Just too fat and every time I when out, I just knew I was going to have a heart attack. Change to a my current 12-27 without having to go to a longer cage. Really works great, but even with the weight lost ( 50lbs so far), I am still around 230Lbs. I to have had 3 trip under the knife with my knees. ( football, baseball, dirt bike riding, ect.) rode hard and put away wet as they say. I keep looking at gear ratio like a motorcycle. One tooth in the front equals 3 in the back, but based on your numbers, it is not quite the same. Was just trying to take a little more strain off the knees. I do use the big ring a lot more now on the flat and small hills, so maybe not is all lost. No reason to spend the bucks for such a small amount. But then again, I spend more than that to change out the cassette. Based on the numbers and how I am riding now, I may run out of gearing on the flats with the small ring. Oh well live and learn. Thank you for your help Joc Gummee. Yep they do make a 33. Not cheap and made only of Ti. I am not that big of a weight wienie. Using Ti on my bike is like taking a sun chair off the Queen Mary and bragging about how much lighter it is.