Hi to all   Firstly Bruce refers to spur in his reply but I think he meant rim  The type of sprocket he shows in the diagram is  a rim sprocket and they are very good  as you can change them over very quickly  Of course you have to buy the drum as well  and if Bruce has a drum and rim kit for the  Mac 10-10 then you are very lucky indeed . 
 I see in your early posts the pics of the bar aet that you sent in had image numbers  given and I was able to view the pics easily by clicking on the link but later post where you say you are sending pics of the sprocket  did not have image numbers  and  I cannot see how to find those pics  .  Serves me right for not keeping up with the updates to this site. 
 No doubt you will set me right on how to find the pics.
  I was thinking about the rim and drum set up  and  although it  may not be required in this case ,as it looks like Bruce may have a new one,how much trouble would it be to  unbraze the spur  sprocket off and replace it with a hub taken off  say a new drum aor even a used drum .  P
 Perhaps this would be a new topic in another forum.. 
Anyway I would be pleased if someone will tell me how to access the pics that Brian sent on the sprocke.............. Maybe I should say  :Thanks Bruce : in anticpation Cheers to all Joe Brown