You are reading a single comment by @ChrisNW and its replies.
Click here to read the full conversation.
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
@ChrisNW
There is a very small difference in headset diameters between ISO and JIS headsets. According to Sheldon, JIS is 30mm and ISO 30.2mm. Crown race size also differs by 0.2 mm too and works the opposite way (ISO dia smaller than JIS).
Therefore it stands that if you have a loose JIS headset, you could get it reamed to fit ISO instead, but you'd also have to remove some material from the crown too, unless...
...has anyone ever mixed JIS crown race with ISO cups?