I run a 46/17 and keep about the same average speed as my geared bikes. I set my personal avg spd record on my Wabi at 18.4 mph over 30-something miles. I used to run a 48 but with a 46 I can keep a more comfortable cadence without burning out and my average speed didn't drop any. Obviously climbing and headwinds are slightly easier. Top speed may have dropped a couple of mph's but who cares.