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

[Andrew Gorman]

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!

 

[kenji]

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

 

[Andrew Gorman]

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.

 

[sailorbenjamin]

Interesting. Thanks for the link.

 

[chucksoldbikes]

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