Originally Posted by Monster Pete

It's better to set up the bike such that 3rd gear is your level-ground gear. 1st and 2nd are then usefully placed for acceleration in traffic, climbing hills and combating headwinds. If you spin out going downhill, just coast. Most of your riding will likely be done in 3rd gear- particularly if you ride a single speed at all- with 1st and 2rd as your backup gears.

One thing you do need is to be able to pedal through a wide power band. If you're used to a bike with a 9 or 10-speed derailleur system, you may struggle somewhat with the widely-spaced gears of a 3-speed. However, this capability comes from going out and riding the thing.