steel:
http://www.jtsprockets.com/catalogue/sprocket/JTR269
aluminum:
http://shop.pbisprockets.com/product...&categoryId=17
right now I'm running a aluminum 46, but will probably go back to the 47 next time I have the rear wheel off.
You may also find you do not pick up top speed, but that you'll do the same top speed, but with less revs...