This is interesting. I thought I was running a pretty low gear on my fixie at 39/17. I'm not familiar with the 2:1 concept. Maybe I should put a 19 on back. It is flat here so I'm not worried about having low enough gear, but my primary objective of riding a fixie is spinning. On my ss freewheel I have 48/18 for more all around use. All of my bikes are commuters. Lately, I have mostly been riding the fg.