Square tapers...

suburbanreuben

suburbanreuben

Old School Grand Master
Can someone please help me unravel the mystery of these things?
JIS, ISO, Campy?
Are all of these common on Italian thread BBs, and which fit Campy chainsets?
Ta
 
JIS = Japanese Industrial Standard
ISO = International Standards Organisation
Campag = more or less ISO

Far Eastern manufacturers use JIS by default and Western manufacturers generally churn out ISO taper BB; however, there is nothing to stop them making BB to either standard, but this is the "norm".

I've read that Campagnolo used their own standard but I couldn't confirm this: either way an ISO taper does the job.

The thread and taper aren't dependant on each other but, bearing in mind the above, the majority of Italian threaded BB will be ISO taper.

According to Sheldon Brown, you can mix and match JIS and ISO cranks and BB, but it will affect the chainline and damage will occur when the cranks are removed.
 
ScillySuffolk":2f3yl53r said:
JIS = Japanese Industrial Standard
ISO = International Standards Organisation
Campag = more or less ISO

Far Eastern manufacturers use JIS by default and Western manufacturers generally churn out ISO taper BB; however, there is nothing to stop them making BB to either standard, but this is the "norm".
Click to expand...

Most Stronglight square-taper BBs (often made under licence in Slovakia by Kinex) these days are JIS, and ISO seems to be turning into the less commonly found spec and maybe not so International after all! Royce and SKF (there may be others) seem to make units conforming to both formats.

David
 
I have noticed ISO taper BB spindles (also 2 degrees but "smaller") offer a lot more contact surface area when fitted to a JIS crankset than the other way around you need to insure the arm doesnt bottom out on anything "inboard" on the spindle and there is a few mm for the bolts to pull it all tight without bottomming out at the other end too (and the rings or end of the arms don't hit the frame also)
 
David B":3az4vhyv said:
...ISO seems to be turning into the less commonly found spec...
Click to expand...
With Shimano's dominance and the decline of European component manufacturers, I suppose this is inevitable...
 
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