Hi, I am trying to find out the taper standard for my Sugino Mighty Cranks. They have a JIS stamp on the crank arm, but opinions vary on whether they are actually ISO or JIS. Does anyone on here know for sure?
That’s what I thought, but opinions on the net differ…
Anyway, unfortunately I can’t find an Italian thread loose ball bottom bracket with JIS spindle (do they even exist?!).
-So I will have to match my JIS cranks to an ISO spindle.
-According to Sheldon the cranks will slide about 4.5mm further on when matching JIS to ISO.
-Apparently the ideal JIS spindle length for the Mighty cranks is 109mm.
So am I right in assuming that I can get away with a Campagnolo ISO bb with 113mm spindle? Will that get me a 42mm chainline?
Any help is much appreciated. It’s starting to do my head in!
Serves you right for using Jap Crap on an Italian frame :evil:
I’d use a cartridge BB and forget the headache. Keep in mind that messing jis/iso will only fudge your crank tapers. To quote Sheldon
Taper matching was fairly important back in the day of loose-ball cup-and-cone bottom brackets, because these required regular maintenance/overhauls, and this required removal of the cranks. Every time you remove and re-install a square taper crank, the hole in the crank is liable to get very slightly larger.
In my experience I’d qualifly that Sheldon’s 4.5mm estimate is more like 3mm. That’s where it get’s murky and inexact. The only way is either by trial and error with a few different cups and axle lengths … or … If you really want to do it right get a Phil Wood and be done with it. It allows for a little adjustment to get chainline just right and for the most they are set and forget.