I hear you. I am friends with the guys over at Larry's Cycle Shop, on Flatbush and K, since you asked about Brooklyn. Go in there and ask for Mugsy (though not sure he'll rob a bank with you lol).

They do basic fits for bikes they sell. Not sure what services they offer with bikes purchased elsewhere, but they will hook you up as best they can. Honestly, the shop doesn't even do pro, custom fits. They do the basic, easy bike fit. They probably would only charge you a few bucks, if they charged you at all. Hell, maybe you can get Mugsy or one of his [strike]henchmen[/strike] employees to do it gratis if you buy some bike stuff you need, like tubes, parts, lights, a helmet, or whatever.

I would still highly recommend you call Glen at Piermont regardless of your needs as he is a great guy to talk to about anything on this topic...certainly a helluva lot better than me.