Originally Posted by
LWaB
The only freewheel with an 11t cog was a very rare Suntour that screwed into a 13t AFAIR, so an 11-up straight block freewheel couldn't happen anyway. 13t straight blocks are fairly easy, 12t not impossible. These things haven't been made for a while though...
I am not at home and so can't check, but I am fairly sure that I can Make a 12 t block using the Regina CX6 kit.
I have 3 of those kits in the garage. I seem to remember that I can do an 11 with it though.