I was riding a mountain bike for decades. An old Walmart one. I usually rode it with the family at a casual pace.
When I started commuting last year, I found out very quickly that this bike was not made for longer mileages and higher speeds.
I did look for a bike with a few easy goals: not too expensive, light, and easy to pedal at speed.
My friend had bought a Trek FX earlier last year, and I thought that it hit my goals of what I wanted in a bicycle.
So I bought a 7.4 FX this spring. I couldn't be happier! It's easy to ride fast. It's light enough that I can carry it with one hand. It looks good (but just pedestrian enough that it doesn't easily stand out as a theft target).