gear is 48 x 17 (~74 inches)...not huge. local terrain is rolling hills, no mountains. cadence is right(ish) from high teens to high 20s in terms of speed. i can spin to about 35mph (160rpm) before my form becomes unmanageable, but anything over 30 is busy! under 15mph is a bit plodding...all torque and not on top of the gear. great calculator here:
http://software.bareknucklebrigade.com/rabbit.applet.html
it's quite common to use shorter cranks on road-going fixies to avoid pedal strike (and make for easier spinning), and some frame designs feature a higher BB for the same reason. i run 165s on the bike shown (172.5 on my geared roadie, 180 on my XC SS). haven't had an issue with dragging pedals or the desire to coast through corners. that said, when i started riding fixed i did have a couple nasty jolts from leg lock while instinctively trying to coast over RR tracks or to catch a stretch or such. they have since learned to just go 'round all the time.
i'm planning to do a charity ride in a couple weeks...thousands of riders on 30/75/100 miles routes two days in a row. my plan is 2 x 100 on the bike shown. course is *dead* flat. hope i don't regret it...
you should ride yours...no fear! with clipless pedals and a fixed cog you can generate a surprising amount of braking with your legs. combined with a front caliper, there's plenty of stop. it's strangely addicting...