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68mm or 70mm?!
#1
Hi there, I'm a bit new to this so bear with me... I want to change my 3 piece bottom bracket on my fixie project as no matter what I try there is some play. I want to change it to a sealed unit so have looked online and obviously the standard is 68mm but according to my tape measure mine is more like 70mm or even 71/2mm which I know is probably not possible. It's an old Sun Worksop frame so not sure why it would follow a foreign format. I'm worried that if I buy a 70mm one it won't align with the thread.

My question is: Can I get away with putting a 68mm one on there and tightening it up or will it not work? My crank is branded "Etc" but seems to fit most tapered spindles.

Any help would be much appreciated.

Thanks.
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#2
Pictures !!!

Where are you located? (covering for George Smile )

Based on: https://www.lfgss.com/thread20767.html most like you need a 68mm

Keep in mind there are many different axle lengths to choose from, which need to be chosen to get the correct chain line with your cranks.
Nigel
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#3
Hey!

I am located in London, UK and thought my frame was British standard so I'm guessing 68mm will work. I will try and upload some photos later to help. My current spindle measures in a 135mm total so I will try and find one near that I guess.
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#4
Unfortunately there are several bottom bracket shell widths and several different threads:

68 and 73mm English threaded with a left handed thread, tightens anti-clockwise, on the drive/right side.

70mm Italian threaded with right handed thread both sides.

And some more besides: http://sheldonbrown.com/gloss_bo-z.html - scroll down the page a bit and you'll see a table with the various widths and types.

68 and 73mm English threaded are the most common, followed by 70mm Italian threaded. But, because it's an older Sun Worksop frame, made by Raleigh, it might be a 71mm BB shell with a thread peculiar to older Raleigh made frames.

If the bottom bracket shell width is closest to 70mm, check to see which way the drive side bearing cup undoes. If it undoes anti-clockwise, it's probably an Italian threaded bottom bracket and these are readily available: http://www.chainreactioncycles.com/Models.aspx?ModelID=71369

If it is an old Raleigh size BB, then you'll probably have to hunt around for a NOS (New Old Stock) Raleigh bottom bracket or something like a Phil Woods bottom bracket, for which you can get Raleigh 26tpi cups: http://www.philwood.com/products/bbpages/ssbb.php. The Phil Woods bottom brackets needs cups and a special installation tool, so while it's very good quality and will probably last a lifetime, it's an expensive solution.
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#5
Thanks guys.

I have re-measured it properly and it looks like it's a 73mm so I'll have a look around.
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