Thanks Bob,
I checked for the ISO sizing when I was there tonight with my daughter. No luck. I might just but one and see if it fits. I see these are available everywhere which would be useful if they do in fact fit.
Another question, are Shimano Nexus cogs interchangeable with S/A cogs? I've read that they are but figure someone here would know for certain. I'd prefer to stick with S/A cogs, but so far my attempt to contact bikesmithdesign has been unsuccessful and the only other place I found that has them is in the UK. I'd like to have a backup if necessary.