My fixie is a old alley rat Motobecane witha 22.0mm fork. I replaced the aluminum stem (which was structurally questionable and not quite tall enough) that was on it with a cheap stamped steel Wald unit. Works fine. There are some very long Pyramid-branded steel stems available in 21.1mm. These are nicer than the Wald stems IMO, and are similarly priced.

http://www.totalbike.com/products/se...mid%20Pro/and/

22.2mm is the common old American diameter, and also found on some old Japanese road bikes. It's possible to find some old MTB stems in this diameter salvaged from very old MTBs.

You could probably just sand down a alloy 22.2mm with some emery cloth and lots of elbow grease. If you must have a alloy stem.