Mark Stonich wrote:
"there is more variation in taper size with spindles where the flats are machined than with cheap spindles where the flats are forged."
I've noticed this. Almost all of the JIS spindles (many of these look to be cheap, actually) that I've measured are forged, showing no machining marks, and these quite consistently measure 12.9mm. Very accurate compared to the mostly-machined Campy/ISO spindles.
MS: "Every JIS spindle I checked only went part way into every old Campi crank I tried. Close enough? Maybe, but they aren't making any more of those old cranks. I'd rather use the right spindle than take a chance."
This seems very sensible. I did, however buy one 1990's production bike with a Campy Racing Triple crankset bolted to a JIS titanium spindle. No problems with chainring runout on the stand, and the cranks set precisely and repeatedly to the same chainline after repeated re-installations, but there is in this case an annoying helping of the usual ti spindle flexiness that has the middle ring contacting the chainstay under hard acceleration. Still no runout visible on the stand tho. The campy crankarms seem made of very hard metal.
Fitting JIS cranks to an ISO/Campy spindle may require some metal to be ground off the spindle's ends, lest the bolt head bottom out on the spindle. I've also seen instances where the flat's upper-end radius dug into the inner face of the crankarm, and this could mess up the relationship between bolt torque and actual taper interference fit between spindle flats and the crankarm bore.
David Snyder
Auburn, CA, usa