TPI for an old schwinn

[beachlivin]

Hey everyone, I have what I believe is a 1953 schwinn 26" cruiser with a one piece crank.

I put a new front fork to lower it a bit and the pedals hit the ground during turns. I was looking at getting a sunlite one piece crank at about 4 1/2 inches, but they all say 24TPI.

Is that tpi number compatible with my bike? I read somewhere that mine may be 28tpi.

Does anyone have experience with this? I appreciate any help. Pic below for reference. I can take a more upclose shot if needed.

 

[Bendix]

Schwinn cranks/bb are 28tpi but a new 24tpi bb set is pretty darn cheap.

 

[beachlivin]

Schwinn cranks/bb are 28tpi but a new 24tpi bb set is pretty darn cheap.

I could only find one person mentioning the conversion.

Can I buy a one piece 24tpi crank and use a new 24tpi BB in the existing housing? Sorry all of this is new to me and after a few hours of research I couldnt find anything conclusive.

 

[deorman]

The bottom bracket will accept common cranksets no problem, you will need the bearings and races, and you may need to add or subtract a spacing washer for centering.

 

[Bicycle808]

OK, just to clear things up: the part of the frame where the BB presses into is called the bottom bracket shell. Your bike has an American BB shell, which is compatible with ANY bottom bracket set that's listed as "American".... The trick is, finding the American-sized BB set that's compatible with your crank. Your existing crank, as others mentioned above, requires a 28tpi BB for one-piece cranks. The Sunlite jawn you're considering takes a 24tpi BB for one-piece cranks, which is by far the more common size these days. So, all you need to do is order the cranks and a Wald 1990 BB set.

When it arrives, you'll need to remove ALL of the crank and BB pieces from the Schwinn. The cups, the bearings, all the hardware. You can use the same sprocket and pedals, but the rest of it has gotta go-- you need to have a bare BB shell for the job. (Schwinn BBs take different bearings than 24tpi BBs do, so even the cups are different.) Press the new cups in, install the sprocket (as Deorman said, you may need some washers to get your chainline right and to properly center the cranks), load it all up, and tighten her down. Getting the bearings adjusted on OPCs is about as easy as it gets just remember you want it to spin freely, but with no play. Put the pedals on after you have it all installed, and go for a test ride....

More info here: http://sheldonbrown.com/opc.html

 

[beachlivin]

Thank you!

I ended up finding a 4 1/2" 28tpi from an old BMX bike on ebay.

I was able to reuse all the old BB stuff.

Thanks for the link. Tons of great information.

OK, just to clear things up: the part of the frame where the BB presses into is called the bottom bracket shell. Your bike has an American BB shell, which is compatible with ANY bottom bracket set that's listed as "American".... The trick is, finding the American-sized BB set that's compatible with your crank. Your existing crank, as others mentioned above, requires a 28tpi BB for one-piece cranks. The Sunlite jawn you're considering takes a 24tpi BB for one-piece cranks, which is by far the more common size these days. So, all you need to do is order the cranks and a Wald 1990 BB set.

When it arrives, you'll need to remove ALL of the crank and BB pieces from the Schwinn. The cups, the bearings, all the hardware. You can use the same sprocket and pedals, but the rest of it has gotta go-- you need to have a bare BB shell for the job. (Schwinn BBs take different bearings than 24tpi BBs do, so even the cups are different.) Press the new cups in, install the sprocket (as Deorman said, you may need some washers to get your chainline right and to properly center the cranks), load it all up, and tighten her down. Getting the bearings adjusted on OPCs is ablout as easy as it gets just remember you want it to spin freely, but with no play. Put the pedals on after you have it all installed, and go for a test ride....

More info here: http://sheldonbrown.com/opc.html

 

[Bicycle808]

Glad it worked out for you.

 

[us56456712]

I use one piece cranks from other old American or Chinese bikes, toss the Schwinn crank and races as they are usually all rusted or have a frozen pedals or rusted out pedal threads. I use the new crank and races and reuse the Schwinn bearings, cups and sprocket. I have done this on at least 3 bikes that I can remember and never had a problem. No problem on the Schwinn's with spacing, but I have had that problem on an old Rollfast. I buy cheap kids 20 inch bikes at the thrift store and use the short cranks from these for 26 inch bikes if I want a shorter crank. Many 16 inch kids bikes have an even shorter crank but they usually don't fit as the bottom bracket shell is smaller, so look carefully. I just did this with a 53 Schwinn American, used a Chinese crank and races. The chrome and finish is no where near as nice as on a good Schwinn crank, but this one had the chrome all warn off.

 

[ind-chuckz]

You can still find the 28 tpi.
http://industrialbikes.com/shop/item.aspx?itemid=143