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1938 Rollfast BB Bearings Needed
- Thread starter Trilobite
- Start date
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In the prewar balooner era, there is mainly one type of bottom bracket set, with some caveats. From TOC through the 20s and maybe early 30s there was all sorts of weird stuff, and we see threads posted to identify it all the time. I am ignoring that. By the mid 30s there was a de-facto standard for American bottom brackets.... almost.
That "standard" is a one piece crank with 24 threads per inch and 10 bearing cages. The chainwheel is held on by the inner cone and driven by a bump on the crank arm that is almost always in the same place. The outlier is Schwinn, who had 28 threads per inch on the crank. The 10 bearing prewar Schwinn cages were the same size as everyone else's.
Oh there could be variations, like some bike brands might have a slightly larger bottom bracket tube, requiring a slightly larger OD on the cup. Some cones might be thicker than others, affecting chainline, etc. There were different types of dust cover, sometimes permanently attached to the cone, sometimes not. The 10 bearing cages all theoretically had the same dimensions and were 99% interchangeable in practice.
That changed after the war. Schwinn kept their 28 thread per inch crank threads, but came up with a whole new standard for the bearings and cones. These are the 9 bearing cages. They are slightly smaller.
When I was growing up in the 70s, there were 2 kinds of crank bearing. The 10 bearing cage fit EVERYTHING (except postwar Schwinn), and you could find some good used ones in any junkpile. If you tried to stuff it in a Schwinn cup, it would drag because it was just a tiny bit too big. The slightly smaller 9 bearing cage was a proprietary Schwinn part. Like a lot of proprietary Schwinn parts, you had to go to the Schwinn shop to get those.
In most cases you could take the whole bottom bracket set from one American bike and stick it in another. The caveat was that if you used a Schwinn bottom bracket set, you had to use a Schwinn crank because the threads were 28TPI.
And so it continued into the 80s (and probably the 90s). 9 bearing cages and 28TPI cranks for Postwar Schwinns, 10 bearing cages and 24TPI cranks for everything else.
Between then and now, something funny happened. Many aftermarket bottom bracket sets now have slightly smaller cones and cups and use the 9 bearing cages that used to be for postwar Schwinn only. These sets are for 24TPI non-Schwinn cranks. It is a combination you couldn't even buy back in the day.
Since a majority of new bottom bracket sets use the 9 bearing Schwinn-type cage, they are easier to find on ebay than the 10 bearing cage that used to be the most common.
I don't know where the 12 bearing cage came from. I think it might be a new creation. It directly interchanges with the 9-bearing one, and as such, fits most new bottom bracket sets and also postwar Schwinns.
That "standard" is a one piece crank with 24 threads per inch and 10 bearing cages. The chainwheel is held on by the inner cone and driven by a bump on the crank arm that is almost always in the same place. The outlier is Schwinn, who had 28 threads per inch on the crank. The 10 bearing prewar Schwinn cages were the same size as everyone else's.
Oh there could be variations, like some bike brands might have a slightly larger bottom bracket tube, requiring a slightly larger OD on the cup. Some cones might be thicker than others, affecting chainline, etc. There were different types of dust cover, sometimes permanently attached to the cone, sometimes not. The 10 bearing cages all theoretically had the same dimensions and were 99% interchangeable in practice.
That changed after the war. Schwinn kept their 28 thread per inch crank threads, but came up with a whole new standard for the bearings and cones. These are the 9 bearing cages. They are slightly smaller.
When I was growing up in the 70s, there were 2 kinds of crank bearing. The 10 bearing cage fit EVERYTHING (except postwar Schwinn), and you could find some good used ones in any junkpile. If you tried to stuff it in a Schwinn cup, it would drag because it was just a tiny bit too big. The slightly smaller 9 bearing cage was a proprietary Schwinn part. Like a lot of proprietary Schwinn parts, you had to go to the Schwinn shop to get those.
In most cases you could take the whole bottom bracket set from one American bike and stick it in another. The caveat was that if you used a Schwinn bottom bracket set, you had to use a Schwinn crank because the threads were 28TPI.
And so it continued into the 80s (and probably the 90s). 9 bearing cages and 28TPI cranks for Postwar Schwinns, 10 bearing cages and 24TPI cranks for everything else.
Between then and now, something funny happened. Many aftermarket bottom bracket sets now have slightly smaller cones and cups and use the 9 bearing cages that used to be for postwar Schwinn only. These sets are for 24TPI non-Schwinn cranks. It is a combination you couldn't even buy back in the day.
Since a majority of new bottom bracket sets use the 9 bearing Schwinn-type cage, they are easier to find on ebay than the 10 bearing cage that used to be the most common.
I don't know where the 12 bearing cage came from. I think it might be a new creation. It directly interchanges with the 9-bearing one, and as such, fits most new bottom bracket sets and also postwar Schwinns.
razinhellcustomz
Cruisin' on my Bluebird
I might have a pair , their not new, but you could have them for the price of shipping.. Good looking bike.. RideOn... Eazin..
Hello again, fellow Cabers...
Had zero success getting the Rollfast bottom bracket assembly back together. I had posted several weeks ago on the Cabe about bearings, as when my friend disassembled and boxed everything, unfortunately, the caged bearings weren’t in the boxes. It was suggested, and the resource file indicates, they were 5/16 x 10 balls, so I got those. In one of the boxes of parts were these two “mystery” washers/spacers. I didn’t know if one or both were intended to be bb parts, or if one (or both) of them belong to the headset. If I assemble the bb without a spacer, the chain line is tight to the stays, and the kickstand overlaps with the chainring, no matter where it’s adjusted to on the chainstay bridge. With one washer between the one piece crank dust guard and chainring, it still overlaps the kickstand. With both spacers installed, the chain line is straighter and the chainring clears the kickstand, BUT there are not enough threads for me to use the outer dust shield (keyed), washer (also keyed), and lock nut. Wondering if the bearings are wrong, or I’m just missing something on reassembly. I’ve scoured the Internet for any kind of schematic on the exploded assembly, but nada. And I thought bottom brackets were a fairly easy reassemble... Thanks in advance for any input!
Had zero success getting the Rollfast bottom bracket assembly back together. I had posted several weeks ago on the Cabe about bearings, as when my friend disassembled and boxed everything, unfortunately, the caged bearings weren’t in the boxes. It was suggested, and the resource file indicates, they were 5/16 x 10 balls, so I got those. In one of the boxes of parts were these two “mystery” washers/spacers. I didn’t know if one or both were intended to be bb parts, or if one (or both) of them belong to the headset. If I assemble the bb without a spacer, the chain line is tight to the stays, and the kickstand overlaps with the chainring, no matter where it’s adjusted to on the chainstay bridge. With one washer between the one piece crank dust guard and chainring, it still overlaps the kickstand. With both spacers installed, the chain line is straighter and the chainring clears the kickstand, BUT there are not enough threads for me to use the outer dust shield (keyed), washer (also keyed), and lock nut. Wondering if the bearings are wrong, or I’m just missing something on reassembly. I’ve scoured the Internet for any kind of schematic on the exploded assembly, but nada. And I thought bottom brackets were a fairly easy reassemble... Thanks in advance for any input!
One of your cages looks smaller, is that an illusion? I looked all over and can't seem to find any 10 bearing cages here to take a measurement on. The 2 cages should be the same. Quantity 10 5/16" balls sounds right to me.
Spacers are used under the inner cone to correct chainline, or possibly correct clearance issues. The inner threads on the crank are a larger diameter, and if those washers have a big enough hole to go there, that's probably where they belong. Headest is a possibility I guess. At least one of the headset washers should be keyed though. Are you missing anything up there?
Spacers are used under the inner cone to correct chainline, or possibly correct clearance issues. The inner threads on the crank are a larger diameter, and if those washers have a big enough hole to go there, that's probably where they belong. Headest is a possibility I guess. At least one of the headset washers should be keyed though. Are you missing anything up there?
Thanks so much for responding and assisting. This is like a 1938 jigsaw puzzle. I don’t have any keyed headset washers, just the two shown in the photo-assuming the mount for the truss rods goes above the flat washers with recesses. (Photo)
Both washers fit over the inner threads. I had tried them mounted on the outside of the dust shield against the chainring. I didn’t try them inside the dust shield, between that and the inner cone. (Photo shown with one, then both, laid over to show that they fit over the threads.)
Cheers,
Mark
Both washers fit over the inner threads. I had tried them mounted on the outside of the dust shield against the chainring. I didn’t try them inside the dust shield, between that and the inner cone. (Photo shown with one, then both, laid over to show that they fit over the threads.)
Cheers,
Mark
razinhellcustomz
Cruisin' on my Bluebird
Looks to me the inner cone washer is flipped upside down. Try switching the inner cone washer around.. The bearings look to be two different sizes .. I still have spares if you would like... Let me know... Razin...
Thanks, Razin, J-wagon, Bloo, and all others!
I’ll try mounting one or both under the race, inside the dust shield, and see what that does for the chain line, and if I can get the outer nut on. Newbie here, and the previous bikes I’ve redone didn’t have spacers in the bbs. Appreciate the offer on the spares. The bearings came from the same Wheels Mfg. 10 pack, so might be angle the camera’s at, but you never know. Mistakes happen.
I’ll try mounting one or both under the race, inside the dust shield, and see what that does for the chain line, and if I can get the outer nut on. Newbie here, and the previous bikes I’ve redone didn’t have spacers in the bbs. Appreciate the offer on the spares. The bearings came from the same Wheels Mfg. 10 pack, so might be angle the camera’s at, but you never know. Mistakes happen.
Archie Sturmer
Riding a '38 Autocycle Deluxe
Also, the kickstand should be on the left side, and the chain ring sprocket on the right, (unless I am misunderstanding something).
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