Campy SR crank failure
 

Is it as common as NR failure? I know they're notorious for cracking at the spider, just wondering if Super Record does the same.

They are the same crank, so yes. The rings are what determines NR or SR.

OK, thanks. I wasn't sure if there was any other difference.

the last generation of super record cranks were updated in an attempt to correct the problem..
they are the non-fluted style cranksets

But do they also correct the spider/arm cracking problem?

-Kurt

The spider/arm cracking problems were related to a stress raiser created at the junction of the arm and the crank. I don't know what year, but Campagnolo solved the problem by putting a small radius at that junction. I'm pretty sure but not positive all Super Record cranks arms had the radiused junction. The fluted/non-fluted arms are not related to the arm/spider failure, and to the best of my knowledge are an aesthetic change only.

Was that revision done before or after the CSPC mandated changes? I have an early '80s NR/SR crankset on my '61 Paramount, and it seems to have the same sharp edge as the earlier crankarms.

Well, according to coelcanth, the removal of the fluting was to combat the pedal-eye failure as a result of toe-straps wearing off the aluminum/causing microcracks on these same cranksets.

Take care,

-Kurt

The toe strap story is a new one on me.

As far as I can tell, the revisions must have corresponded with the no flute versions in 1984. I have seen cranks from pre 1973 from 1977, 1978, from 1980,1981, and 1984 all looked for all intents and purposes to be machine in exactly the same way with the sharp edges the only ones with no signs o cracking were the 1984s and 1978s (to the naked eye) presumably because they appeared to have seen VERY little use.

The elimination of the crank arm flute milling was in concert with the added material behind the spyder arm junction. Campy cranks were lathe turned prior on th eback side, these later cranks, by this time Super Record only were CNC milled to get the shapes desired.

Did it eliminate the problem? probably, but soon thereafter Super Record stopped production.

All very interesting posts.

One last question though - is there any striking, visible difference between the post '77 cranks and the pre- CSPC/pre-'77 cranks? I've heard that the arm was placed farther outboard to clear the CSPC-mandated derailer lip, although on the two cranksets that I have (one early, one late NR), I don't seem to see any particular difference.

P.S.: Might as well put my shameless plug in here: I need a pair of NR crankarms. Post '77 preferably. 170-175 OK.

-Kurt

The spindle length was increased by 2.5mm on the drive side, but I can't see the diff on the arms, either. And I think I saw some NR cranks in the for trade section of road bikes. check there.

So now what?
 

So, I just looked at my NR crank that I recently purchased and yes, I have a stress crack. Is there any fix? I was thinking of filing it down a bit to remove the damage and the stress riser. Any thoughts?

i only meant that the flutes were removed at the same time the spider/arm cracking was addressed.. i'm not sure if no-flutes was an attempt to avoid other wear or cracking issues..

btw, i have noticed a very slight difference in pre- and post-cpsc drive side crankarms;
the bulge on the backside of the spider surrounding the bb taper is slightly flatter and has a smaller diameter on the post '77 cranks i have..
i'll attach ssome pictures to try and clarify.. unfortunately it doesn't illustrate well as one set was mounted..
also note the pre-cpsc cranks have been filed to correct some cracking..

1974:
http://farm1.static.flickr.com/227/4...019e3608a2.jpg

1982:
http://farm1.static.flickr.com/230/4...d3006d6497.jpg

coelcanth may have some insight on the date of these (1972 because the 2 dots??) anyway here are some pictures of filing I did to old record cranks, i still have to strip and polish these babies they are the worst condition record cranks I have seen.
http://i83.photobucket.com/albums/j2...ling/177-1.jpg
http://i83.photobucket.com/albums/j2...ling/177-3.jpg
http://i83.photobucket.com/albums/j2...ling/177-2.jpg
http://i83.photobucket.com/albums/j2...Filing/177.jpg

hey cudak. still have those cranks, and judging by the above post about the "bulge" on the backside, I'd guess post '77. there is very little backside bulge. just sayin' is all.

PM sent.

-Kurt

The backside "bulge" near the crank port is part of the solution to the dimensional problem that Campagnolo faced when the CPSC modifications were solved, the CPSC compliant cage is wider due to the forward lip, to make room, more distance was made between the large ring and the backside of the arm, pushing the rings inboard, that is why to take up some dimension, the later cranks appear "flatter" on the back side, and the spindle changed too. This is why one cannot in most cases use a later crank on an early spindle, the chainrings will often hit the chainstay and or the chainline will be off. Another reason later rings have a perimeter pin that is too long to use on early cranks unless the pin is filed shorter.