• Funnily enough I was looking at 3 bottom brackets today to try and work out what was going on. An NJS Hatta, the Token ISO one mentioned above and un55. The token and UN55 were close enough in taper length that I couldn't tell the difference, but the NJS one was definitely shorter than the other two, maybe only by 1 or 1.5 mm though.

    Sheldon also mentioned that the end of an ISO tapers to a slightly narrower end, but if it does it isn't by an amount discernible by my eye when placing them against each other.

    Anyway, the bottom line is I still don't get why the crank wouldn't go on to the Token ISO BB, other than it might just be poorly machined. I would try the cranks on the NJS BB but the drive side cup is stuck in another frame at the moment...

    Thanks for the help anyway guys.

  • I'm struggling with the new forum's search function, but if you trawl Tester's posts he does go into more detail (search: tester/sheldon/taper).

    My understanding is that JIS are measured up to the 1mm chamfer, where as ISO are end-to-end, hence the 2mm difference; ie 109mm JIS = 111mm ISO.

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