> Marcus wrote:
>
>So today's worry is that the Campy SR cranks are
bottoming out on the
>spindle. The crank arms are tight, but I am not
loving the chain line.
>Are my cranks toast? The spindle is a Campy steel.
I can't remember the
>numbers on it, and it took awhile to get the BB
adjusted right, so I
would
>prefer not to take it apart again if I can help it.
I know, I should have known, but here we are.
Campagnolo and most European bottom bracket axles (the only true axles in a bike) are ISO. Shimano axles are JIS. Sheldon Brown summarizes the differences between the two thusly:
"ISO vs J.I.S. Standard Martin Trautmann posted on rec.bicycles.tech:
L_right = 18 +0.5/-0 mm L_left = 16 +0.5/-0 mm Dimension across flat 1.5mm from end: 12.6mm +0.02-0.05 Spindle end to bolt seat: Loose: 3mm Tightened: 1.5mm min.
Yet another source claimed that the squares of Campa, Mavic and Stronglight (ISO) are smaller than Shimano and Suntour (JIS) with the result that JIS cranks will move about 4.5 mm further in.
This may conflict with the end of the square and result in a loose fit or braking stress. for ISO cranks on JIS squares there's less contact area between crank and spindle, since the crank does not slip perfectly on the spindle. The result again is a higher risk of braking the crank.
But assuming those 4.5 mm and 2 deg, ISO is about 0.3 mm smaller than JIS (2 * sin 2 * 4.5 = 0.3)?
[Here's the important part for the case at hand--jjt]
ISO cranks (Campagnolo, Stronglight, others) won't go as far onto J.I.S. spindles as they ideally should. J.I.S. cranks (most Japanese models) may bottom out if installed on ISO spindles. In practice, you can very often get away with mixing these sizes, as long as you select an axle length that gives the desired chainline."
Consequently, because the JIS axles are slightly thicker, you may be able to switch to JIS and recapture your offset as the crank will not slide quite as far up on the taper as on the same length ISO axle.
However, THIS IS NOT WITHOUT RISK. (As my legal education takes over.) Because the Shimano/JIS axles are "fatter," you also risk splitting your ISO Campy crank if you tighten them down to much and JIS axle turns out to be too wide.
There is no free lunch.
BTW, iirc, Phil Wood makes both JIS and ISO tapered axles.
Good Luck!
===== John Taglia Chicago, Illinois
__________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com