Bicycle Mechanics - Bottom Bracket

Hello,

I have an old Nishiki (early 80's vintage) that I would like to upgrade the cranks and bottom bracket. There's tons of cheap stuff on eBay, but I don't what size, threads, whatever, my existing BB is. How can I figure it out?

Thanks!

Brian

Hello,

I have an old Nishiki (early 80's vintage) that I would like to upgrade the cranks and bottom bracket. There's tons of cheap stuff on eBay, but I don't what size, threads, whatever, my existing BB is. How can I figure it out?

Thanks!

Brian
English thread,most likely 68mm BB shell widh,but measure to be sure it isn't 73mm. BB has to match crank with respect to spindle length, and interface(JIS,ISO, octalink,isis....).

Hello,

I have an old Nishiki (early 80's vintage) that I would like to upgrade the cranks and bottom bracket. There's tons of cheap stuff on eBay, but I don't what size, threads, whatever, my existing BB is. How can I figure it out?

Thanks!

Brian
I have a 1983 Nishiki Sport and a couple other 80's Japanese bikes. They ALL use 68 mm English threaded bottom brackets. This is great because it means you can use a modern cartridge bottom bracket (you can get one for $10 at Nashbar).

Don't worry about the length if you're getting new cranks too: the new cranks will specify the appropriate length of bottom bracket. Though if you get slightly the wrong length you can often correct it by fiddling with the derailer adjustments.

Thanks Sydney!

So when I search eBay I see lots of octalink BB stuff that says 68 x ~109.5 English Octalink. So:

68 is the diameter in mm of the threads of BB?
109.5 is the length of the BB shaft?
English is the thread cut?
Octalink is a type of shaft end? Will Octalink work for most 105, Ultegra, Durace that are marked Octalink?

Thanks Sydney!

So when I search eBay I see lots of octalink BB stuff that says 68 x ~109.5 English Octalink. So:

68 is the diameter in mm of the threads of BB?
109.5 is the length of the BB shaft?
English is the thread cut?
Octalink is a type of shaft end? Will Octalink work for most 105, Ultegra, Durace that are marked Octalink?

68 mm is not the diameter of the threads, it is the WIDTH of the bottom bracket shell, the part of the frame that the bb screws in to.

109.5 mm is the spindle length, correct.

English means that the right cup is left-hand threaded and the left cup is right-hand threaded (this is now the standard for all new bikes).

There are unfortunately two DIFFERENT types of Octalink (read this: http://sheldonbrown.com/gloss_n-o.html#octalink). Make sure that they match :)

68 mm is not the diameter of the threads, it is the WIDTH of the bottom bracket shell, the part of the frame that the bb screws in to.

109.5 mm is the spindle length, correct.

English means that the right cup is left-hand threaded and the left cup is right-hand threaded (this is now the standard for all new bikes).

There are unfortunately two DIFFERENT types of Octalink (read this: http://sheldonbrown.com/gloss_n-o.html#octalink). Make sure that they match :)68 is the bb shell width and means english thread.

68 is the bb shell width and means english thread.Last I checked, 73 mm was English thread too. What the 68 mm and 73 mm bb's have in common is the threading, which is what I take to be the "Englishness" :P

You guys are awesome. I'm an expert now!

Thanks

Brian

68 is the bb shell width and means english thread.

... or, on certain older European bikes, French or Swiss thread ...

However, for anything less than 15 years old, I think the rule, "68mm shell width implies English threading and 70mm implies Italian threading" holds.

... or, on certain older European bikes, French or Swiss thread ...

However, for anything less than 15 years old, I think the rule, "68mm shell width implies English threading and 70mm implies Italian threading" holds.Thanks for clearing that up for me... ;). But the context was Nishiki.