Ok, test fitting my 7600 crankset…Seems to be a lot of conflicting info. Some say JIS. Some say 109 ISO. Some say all the late production 7410 BBs are JIS anyway…
Looked around couldn’t find any ISO BBs. Had a crack with a 107mm UN52 JIS BB, cranks seem to fit fine on the tapers, admittedly they could press on further but they come to within a hair of the marks from the previous owner’s bb axle in Japan.
I haven’t really wailed on the crank bolts as yet, as I am slightly afraid of stretching the tapers.
So…Chainline looks to be about 43-44mm which is about right?
Non-drive crank sits a poofteenth (e.g. 2mm maybe) further out from the stays but that could be frame design.
Q-factor seems to be about spot on shimano’s measurement of ~140mm.
Will it wreck them if I ride it as is while waiting for a 109 ISO Hatta one to arrive? I will order a Hatta R9400 next week, but wouldn’t mind doing literally a couple of kilometres on it beforehand.
No, I’ve got lots of friends who mix and match, but you’d be better off running a JIS BB with a shorter spindle as the crank arms will sit further out than they would on the spindle than on an ISO BB. Pretty sure the dura-ace track cranks are ISO (or Octalink).
If Sheldon is right, then they’d be about the same as a ~111 ISO spindle, when fitted to a 107 JIS spindle. Which seems right as they’re within a mm or so of Shimano’s chainline and Q specs which are allegedly for 109 ISO (but have seen this contradicted).
Am I correct in inferring ISO cranks will need a proportionally narrower JIS spindle for the same chainline and Q?
The danger is more in bottoming JIS cranks on the skinnier, longer tapered ISO spindles? and;
The potential for damaging either is mostly in repeatedly removing/refitting on non matched spindles damaging the taper?
Update…
Found a 111mm Campagnolo BB at work (Veloce I think), snuck it in, cranks pressed considerably further onto the taper, chainline etc is pretty much spot on, so I suggest ISO is it, but it looks like JIS will work in a pinch.
I used a 7610 BB with my 7600 cranks. No issues. I think rhe spindle is 109 but I didn’t even look. I didn’t really expect to have any issues with 7600 cranks / bb / hubs.