Schwinn Bottom Bracket options / opinions

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I have a late 50s early 60s schwinn typhoon.

I want to run a 3/32 chain on it for now to allow for gearing. I have the framset spaced to 135 in the rear and have a claw mount rear mech that appears to line up.

The original 46t 4 circle ashtabula sprocket is 1/8 chain only. This is kind of a bummer because i like the look of that ring alot.

That leaves me with 3 options

1. Find an affordable bmx spider for 1 piece cranks at 110 bcd and a 46t chainring from any road bike crankset. Run the stock cast OPC with that.
2. Run a bottom bracket adapter that converts this type of bb and get a threadless cartridge style bb. I am showing about 20 bucks for the adapter and probably $15 for the cartridge bb. I have several old road cranksets that i could use. I dont know how much weight id be saving in the end if i went this route and i dont know if really care. https://images-na.ssl-images-amazon.com/images/I/71XHgAQ6U9L._SL1500_.jpg
3. Get a sunlite 46t ashtabula 3/32 chainring and run the stock cast OPC with that. These are about $10. https://images-na.ssl-images-amazon.com/images/I/518hgH3qluL.jpg

Thoughts?

 

[Dizzle Problems]

You’ve pretty much coved the options. There is also American bb adapters with a square taper spindle so you could run an old road crank.

As far as opinion, I’d prob go with one of the adapter options vs the opc. Main reason being chain line. If you respaced the rear, the original chain line is effected. By using one of the adapters, you can get the chainring a little father out for better chain line.
I suppose you could do this with a opc too by adding a washer behind the chainring, but run the risk of running out of threads on the non drive side.

 

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Yup...that was my thought too.....washers behind like you mention or new road crank + adapter and then i have man differnt bb options for length and could still do spacers to dial it in if needed. It is the spendier of all the options but not by much.

I dont know what the original rear spacing is or was. Is it 135? I got this frame second hand. I imagine the rear has been respaced. Id be surprised if the rear is 135 stock.

I got the fat franks to fit under the original fenders and boy is it tight but it looks great.

 

[Dizzle Problems]

Original rear spacing would have been 110, for a coaster hub.

 

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Thanks. That confirms then that the place i got it from had already done the spacing to 135.

 

[RustySprockets]

Have you considered grinding the original sprocket to accept 3/32" chain? Schwinn also produces a modern sprocket found on their multi-speed cruiser offerings--it looks just like the vintage four-circle.

 

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Have you considered grinding the original sprocket to accept 3/32" chain? Schwinn also produces a modern sprocket found on their multi-speed cruiser offerings--it looks just like the vintage four-circle.

Nope. I did not know this. I am now looking into finding one of these.

 

[deorman]

Fits 3/32 some scuffing from use and bucket storage $10.00 shipped.

 

[RustySprockets]

Well, there you go...a nice shamrock solution for not much money. Of course, you're stuck with the OPC if you go that route.

 

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dang it....i found and opted for a sweetheart repop i found online this morning before i saw this. If that doestn work out i am surely going the adapter route and probably come Sugino cranks i have already.

 

[deorman]

Heart sprockets are awesome.

 

[Dizzle Problems]

Out of curiosity, what set up do you intend on running? 3/32 will work 5-8 speed, 9,10, and 11 are slightly more narrow.

I've been wanting to cold set a frame to 135 to run a one by 9 for a bit. But don't have a frame I feel comfortable doing it to

 

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I am going to try a 9sp since that is what i have a on hand. I might dial it back to 8 if i cant get things to shift correctly. I am going with a friction shifting setup so i dont think i will have an issue.

 

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ok....sprocket is in and on. I was hoping to use one of my old 9 speed road chains but i am finding it is way too short. This is likely due to the longer stays. Im going to need to join 2 speed chains. New they come in 116 links and that isnt enough. I will probably go with kmcs 9sp. They are reasonably priced. I do beleive they are about 15 bucks. Looks like another 30 bucks in chain. Maybe i can find some used chain at the coop. That might be a better way to go.

 

[RustySprockets]

When a customer shortens a new chain at our co-op, I toss the cut bits into a baggie for safekeeping. Later, I can reassemble them into a never-used chain for free. Yes...I really am that thrifty.

 

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i have a bucket of chain bits as well but no 9sp. It is mostly single speed stuff. I dug through it all and no luck. I bet my local coop has a bit just like you mention though. I am going to check it before ordering new. This is going on a cruiser style bike so i am not concerned with it breaking or being under too much stress like on a road or mtb.

 

[Indyjps]

Fits 3/32 some scuffing from use and bucket storage $10.00 shipped.View attachment 67436

Deorman, or other informed members. Ive seen the same sprocket on 60's-70's Schwinn's with derailleurs. Would the derailleur version of this sprocket fit 3/32 chain?

 

[deorman]

Yep.