crank/bb question
09-01-15, 09:58 AM
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crank/bb question
I'm in the processes of rebuilding a ss bike, and I noticed that the frame (sekine, not sure of the model) had some weird bb dimensions.
To my understanding, english thread bb are 68mm, but on my frame its 70mm wide.
I'm planning on fitting the bike with the vuelta pista crank.
https://www.amazon.ca/Vuelta-Pista-Tr...productDetails
My current bb has too long of a spindle for me to use that crankset, so I'm planning on purchasing a new bb
Do you guys have any suggestions for CHEAP (<$30) and RELIABLE bb?
Thanks!
To my understanding, english thread bb are 68mm, but on my frame its 70mm wide.
I'm planning on fitting the bike with the vuelta pista crank.
https://www.amazon.ca/Vuelta-Pista-Tr...productDetails
My current bb has too long of a spindle for me to use that crankset, so I'm planning on purchasing a new bb
Do you guys have any suggestions for CHEAP (<$30) and RELIABLE bb?
Thanks!
09-01-15, 10:25 AM
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When finding a modern sealed BB (like a shimano, etc) it can seem crazy but if you use a few simple processes you can figure it out. Highly reccomended: Sheldon Brown has a graph that shows what happens when you put the wrong/correct BB in the wrong/correct BB shell. Sheldon Brown's Bottom Bracket Size Database
With older bikes the width of the shell is a good place to start but the size of the BB threads and the absolute give away is the rotation of the cups. Likely if they screw on opposite threaded its english. Don't worry that the BB is near 70mm. I have an old Bianchi that is most definately an Italian BB, however, the BB shell measures a lean 67 wide, not even close to a 70mm called for in spec. Guess what I do? I wrench it down 2 more mm. Same with you, just get the correct BB and thread it on carefully it will find it's own level. The thread size and rotation is really important as is the other variable of finding your spindle width but it looks like you got that.
With older bikes the width of the shell is a good place to start but the size of the BB threads and the absolute give away is the rotation of the cups. Likely if they screw on opposite threaded its english. Don't worry that the BB is near 70mm. I have an old Bianchi that is most definately an Italian BB, however, the BB shell measures a lean 67 wide, not even close to a 70mm called for in spec. Guess what I do? I wrench it down 2 more mm. Same with you, just get the correct BB and thread it on carefully it will find it's own level. The thread size and rotation is really important as is the other variable of finding your spindle width but it looks like you got that.
Last edited by Night_shift; 09-01-15 at 10:31 AM.
09-01-15, 11:21 AM
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When finding a modern sealed BB (like a shimano, etc) it can seem crazy but if you use a few simple processes you can figure it out. Highly reccomended: Sheldon Brown has a graph that shows what happens when you put the wrong/correct BB in the wrong/correct BB shell. Sheldon Brown's Bottom Bracket Size Database
With older bikes the width of the shell is a good place to start but the size of the BB threads and the absolute give away is the rotation of the cups. Likely if they screw on opposite threaded its english. Don't worry that the BB is near 70mm. I have an old Bianchi that is most definately an Italian BB, however, the BB shell measures a lean 67 wide, not even close to a 70mm called for in spec. Guess what I do? I wrench it down 2 more mm. Same with you, just get the correct BB and thread it on carefully it will find it's own level. The thread size and rotation is really important as is the other variable of finding your spindle width but it looks like you got that.
With older bikes the width of the shell is a good place to start but the size of the BB threads and the absolute give away is the rotation of the cups. Likely if they screw on opposite threaded its english. Don't worry that the BB is near 70mm. I have an old Bianchi that is most definately an Italian BB, however, the BB shell measures a lean 67 wide, not even close to a 70mm called for in spec. Guess what I do? I wrench it down 2 more mm. Same with you, just get the correct BB and thread it on carefully it will find it's own level. The thread size and rotation is really important as is the other variable of finding your spindle width but it looks like you got that.
so if i'm understanding it correctly,
i can get a slightly bigger 73mm bb (since my crank shell is 70mm) with a 108mm spindle (which is what the crankset requires), i'm gold?
09-01-15, 01:51 PM
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No, I would still get the standard 68mm english with what ever spindle size the crank you are using recommends.
I'm saying don't worry the shell is a little fat, the threading type is most important. that 68~70mm difference could be due to machine standards back then, etc. The spindle length is it's own thing.
I'm saying don't worry the shell is a little fat, the threading type is most important. that 68~70mm difference could be due to machine standards back then, etc. The spindle length is it's own thing.
09-01-15, 04:13 PM
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wiggle.com | Miche Primato Track Bottom Bracket | Bottom Brackets
09-01-15, 05:44 PM
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iso/jis
JIS
Vuelta Cartridge Bearing JIS Square Taper Bottom Bracket
Old Miche is ISO, new Miche is JIS.
Vuelta Cartridge Bearing JIS Square Taper Bottom Bracket
i saw on another thread that someone was able to use the miche primato bb no problem. think i'm gonna go for that!
wiggle.com | Miche Primato Track Bottom Bracket | Bottom Brackets
wiggle.com | Miche Primato Track Bottom Bracket | Bottom Brackets
09-01-15, 08:46 PM
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thanks for all the help!
vuelta bb it is!
