Bottom bracket size for 76 Raleigh Grand Prix
08-05-20, 03:04 PM
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Bottom bracket size for 76 Raleigh Grand Prix
Don't really know much about sizing on old bikes, I thought this forum would be a good place to ask
08-05-20, 03:26 PM
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Hello Grox02 and welcome to the forum!
the bottom bracket shell width is 71mm
the bottom bracket shell thread is 26TPI
the drive side is lefthand threaded
the non-drive side is righthand threaded
Hope this helps.
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Hello Grox02 and welcome to the forum!
the bottom bracket shell width is 71mm
the bottom bracket shell thread is 26TPI
the drive side is lefthand threaded
the non-drive side is righthand threaded
Hope this helps.
-----
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08-05-20, 09:47 PM
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Thanks! This seems like the exact answer I was looking for!
08-05-20, 11:19 PM
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My 76 has a regular 24tpi bottom bracket that is 68mm.
08-06-20, 02:10 AM
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08-06-20, 06:12 AM
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Thank you!
That is certainly surprising.
Are you able to read the factory source code for your example?
https://www.kurtkaminer.com/TH_raleigh_serials.html
Yet another of those famous Raleigh oddities!
The forum had a Grand Prix last week whose source code was letter A and no letter A is shown at the registry...
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Thank you!
That is certainly surprising.
Are you able to read the factory source code for your example?
https://www.kurtkaminer.com/TH_raleigh_serials.html
Yet another of those famous Raleigh oddities!
The forum had a Grand Prix last week whose source code was letter A and no letter A is shown at the registry...
-----
08-06-20, 06:57 AM
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Here it is built as a single speed then as a dingle speed.
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08-06-20, 07:57 AM
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I have a later '70s Grand Prix (Canadian made) and it has a standard ISO BB. At least, shell width and threads are the standard. The original BB cups were quite narrow, though, and the threads in the frame were not cut far enough in to allow the wider cups of a modern cartridge BB to be fully installed. I had to Dremel a bit of seat tube and downtube away inside the shell to make room, then the LBS dusted off their BB taps and extended the threads for me.
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08-07-20, 11:02 AM
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Hello again Grox02 ,
Hope we have not confused you too much with this discussion!
For most Raleigh models it is pretty simple:
a) a 71mm width bottom bracket shell equals 26TPI threading
b) a 68mm width bottom bracket shell equals 24TPI (BSC/ISO) threading
There are some small wheeled Raleigh models such as Shopper, Twenty & Folder which have 76mm width bottom bracket shells. These also have the 26TPI threading.
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Hello again Grox02 ,
Hope we have not confused you too much with this discussion!
For most Raleigh models it is pretty simple:
a) a 71mm width bottom bracket shell equals 26TPI threading
b) a 68mm width bottom bracket shell equals 24TPI (BSC/ISO) threading
There are some small wheeled Raleigh models such as Shopper, Twenty & Folder which have 76mm width bottom bracket shells. These also have the 26TPI threading.
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08-07-20, 02:12 PM
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If I interpreted Sheldon's article correctly, the rule of thumb for Nottingham built bicycles (which would include Grand Prix) is cottered crank = 26 tpi threading, cotterless = 24 tpi. Of course it's possible that someone may have replaced the crankset from one type to another, and that your shell width rule of thumb is more accurate - unless someone refaced the shell a few times. 
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08-07-20, 02:30 PM
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Nottingham facility -
the Grand Prix model has been produced in at least eight different facilities
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Nottingham facility -
the Grand Prix model has been produced in at least eight different facilities
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08-07-20, 04:06 PM
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08-08-20, 06:12 AM
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Gazelle built bikes are all 68mm, 24tpi. I have a 74 Grand Prix that is 24 you for both headset and bottom bracket.
