# Thread size on Schwinn Pre-war freewheel and post-war fixed cogs?



## Andrew Gorman (Dec 11, 2010)

Hi all.  I am trying to  jimmy the gearing on a 1947 New World fixed gear and was wondering  if any other rear sprockets would fit the post-war aluminum fixed rear hub. Modern threaded freewheels are all too small, but I am able to thread the  8 tooth cog  onto a pre-war dural featherweight hub set up for a freewheel, so the threads should be the same.  I was pretty excited when I found a 20 tooth Williams chainring to replace the current 24, BUT the smaller ring just misses the dimpled area on the chainstay and fouls. Looking at the bike closely after too much time hanging in the rafters, the 24 tooth is about as small as will fit and the current gearing is too tall for an old fat rider on city streets.  My options now are  longer cottered spindle or a larger rear cog IF Schwinn didn't use some bizarre size. All the coaster cogs I have tried are all too small in threaded diameter.  Are there other makes of rear cogs that will fit the Schwinn?
Thanks!


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## kenji (Dec 12, 2010)

Quote sheldon brown:
"_Older coaster brakes used threaded sprockets and lock rings, as with track hubs. Although they are the same in theory, they commonly used different threading, so they are not usually interchangeable with track sprockets. Threaded sprockets made for coaster brake use commonly had a radial slot at one point, to make it possible to replace a broken spoke without needing to remove the sprocket_
http://www.sheldonbrown.com/coaster-brakes.html#sprockets


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## Andrew Gorman (Dec 15, 2010)

Actually this little widget might do the trick:
http://www.thethirdhand.com/index.c...sc=Cup Spacers&item_id=BR-FWS3&id=29227837997
A spacer to push the fixed cup of the bottom bracket out  2mm.  I'd be VERY impressed if any of the local bike shops have one, though.


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## sailorbenjamin (Dec 16, 2010)

Interesting.  Thanks for the link.


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## chucksoldbikes (Mar 16, 2011)

take the  fixed cup  to thr  machine  shop and have  them  make  what u  want to  fit
make it      2mm longer  and  the rest  the same
itll work chuchsoldbikes
i make alot of   things  like   botton berring  brackets  for the  springer   forks just like the schwinn ones u cant  tell them apart


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