Since my two posts on here I've geared down again, I'm still on 165 cranks, but I'm now riding a 44x18 set up which gives me a 65 inch gear, its a blast to ride. I've slightly compromised my top end, but I'm still topping out around 20mph and averaging around 15mph, climbing is easier but descents are more interesting. What I think has happened is 4 years on fixed has smoothed out my pedaling and made me better at spinning, It did a similar thing when I was riding fixed in the late 1980's.