Hi SS group.. I’m attempting my first single speed conversion on a 1977 Schwinn Traveler and need help figuring out my bottom bracket/crank situation. I want to get a more modern SS crank around 44T or so but not sure what to do about the BB. Attached are some pictures of my current crank and BB, which is just smoothed cups for the bearings. I assume I need to remove and replace with a modern retrofit BB but not sure?

Any guidance is greatly appreciated!

I haven't worked with enough American/Ashtabula bottom brackets to be sure, but I think you need something like this - https://www.danscomp.com/truvativ-am...waAspfEALw_wcB

maybe something like this...One piece crank to 3 piece square taper.

https://www.amazon.com/Fenix-Cycles-...f&gad_source=1

I used something like that on my Super Sport.

Funny thing though. The boat anchor Ashtabula crank lasted twenty years, and the conversion didn't last five. All post apocalypse bikes will have Ashtabula cranks.

This is great, thank you!

😆😆

This is the method I have used. It allows me to select the bottom bracket that achieves the best chain line.

Thanks, so if I install this kit then it allows me to install any standard threaded bottom bracket and then get a crank that works with that BB?

Yes. That is what has worked for me.

Also, a quick tip for installing the adapter:

1. Lube the bottom bracket shell and press both sides of of the adapter into the shell.
2. Install the drive side portion of the bottom bracket.
3. Once the drive side of the bottom bracket is snug, continue turning it with your bottom bracket tool until the holes for the fastening bolts line up with the holes in non-drive side adapter.

This is easiest way I have found to line up the holes for the adapter bolts.

Great thank you!

I used a Truvativ adapter for this bike. You have to hammer out the bb cups first.

I used the truvativ adapter and got it done, here’s the finished product. Thanks guys!

Looking good.