Originally Posted by
spcialzdspksman
Top speed will be capped.
I'd say >75" is best. If you compare it to the spectrum of a road bike, that's probably about mid-ground gearing, whereas 60s will be on the easier gearing.
Whenever you have only one gear ratio, there is an inherent compromise. To say that any gear "is best" ignores this entirely. The "best" gearing for a situation is dependent on topography, personal preference, and fitness (both level and type).
Also, top speed for any ratio is "capped" for many street fixed gear riders by their ability to spin, not their gear choice. Faster spin (with good technique) > enormous gear inches.