Spinning is less of a relevant issue for fixed gears, because you cant change gears to keep a constant high cadence,

thus as long as you have gear in the upper sixties to upper 70s, you will be spinning a high a cadence when going fast, and a low cadence when going slow, unlike a road bike where people try "spin" a higher constant cadence, regardless of speed.

so for the most part unless your running a silly high/low ratio, the notion of "spin" shouldn't really be a big factor in your day to day riding.