I have been running 32x20 for a long time, I knew I could run less but when Robbie gave me and endless 18T cog as a birthday gift I had to put it on. I picked a place that didn't have too much climbing. I was immediately impressed and was soooo much faster everywhere. I even cleaned broken back climb. I also set a whole bunch of personal records! I am excited to see how it will do on Mine.