A friend of mine asked me to think about how much it would cost him to put together a decent single speed cross bike for commuting (on as tight a budget as possible). Off the top of my head, I was thinking Surly Crosscheck or the IRO Rob Roy. Most of it I feel I have a decent notion of what to use, but I really have no idea what SS crossers use for cranks. Do they use the same stuff that fixed riders do? Do they use road cranks? Do they typically go 3/32 or 1/8?