infamous campy SR crank spider web hairline crack: real question
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infamous campy SR crank spider web hairline crack: real question
yes. that. the notorious crack, more like hairline prediction of a crack in the back of the spider junction. i've read/searched tons of articles/posts inc. the ones on C&V here yet with some real curiosity.
will it really break under 'ordinary' riding? non-criterium, non-compete, less than a few miles daily city riding, i mean. i've read horrors breaking at pedal eyes, but didn't really see the cases spider arm really "broken"? i understand no one can guarantee it, just asking 'in general', common sense. should a less-than-a-millimeter hairline be really a panicking thing or like hey, it's common just ride with a caution?
i do have round files, am capable of filing/sanding things, and it doesn't seem to be too hard to file a couple mils away. should i just do it and forget about it?
got one pair that had looked totally fine in the pics, then i see it in person. less than a millimeter, obvious initiation that i can also see from the outside flat too. (and trust me, not the first time i see this). yes i'd easily return 'em unless it's from South Africa—and the one i had to wait nearly two months to arrive... under current situation, it'll most likely take another two months to sort it out—return, refund etc etc.
i mean, the problem is always, that SR/NR crank arms are too pretty to give up...
will it really break under 'ordinary' riding? non-criterium, non-compete, less than a few miles daily city riding, i mean. i've read horrors breaking at pedal eyes, but didn't really see the cases spider arm really "broken"? i understand no one can guarantee it, just asking 'in general', common sense. should a less-than-a-millimeter hairline be really a panicking thing or like hey, it's common just ride with a caution?
i do have round files, am capable of filing/sanding things, and it doesn't seem to be too hard to file a couple mils away. should i just do it and forget about it?
got one pair that had looked totally fine in the pics, then i see it in person. less than a millimeter, obvious initiation that i can also see from the outside flat too. (and trust me, not the first time i see this). yes i'd easily return 'em unless it's from South Africa—and the one i had to wait nearly two months to arrive... under current situation, it'll most likely take another two months to sort it out—return, refund etc etc.
i mean, the problem is always, that SR/NR crank arms are too pretty to give up...
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What's scary about those cracks is it can literally be just the tip 9f the iceberg, where there's actually a lot more damage within the crank, under the surface, not visible from the outside......pretty much a potential "silent killer".
Easing it out with a file can give you an idea on how deep it really goes into the crank.
Easing it out with a file can give you an idea on how deep it really goes into the crank.
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FWIW I rode a campy crank with a small starter crack like that in the web for years, before I finally chickened out and replaced it. I think I've seen a picture once of someone who let it go until it actually failed. That would take a while. Keep a careful eye on it and if it starts to get substantially bigger, stop riding it. I'm not sure if filing the web now that a crack has started will be any help.
This isn't like cracks that begin at the pedal eye or across the main body of the crank arm. Those fail relatively quickly and often dangerously, and any crank with that type of crack should be retired immediately. I broke a crank completely through without warning once, at it was both disconcerting and potentially dangerous. From then on I learned my lesson and watched carefully for cracks.
This isn't like cracks that begin at the pedal eye or across the main body of the crank arm. Those fail relatively quickly and often dangerously, and any crank with that type of crack should be retired immediately. I broke a crank completely through without warning once, at it was both disconcerting and potentially dangerous. From then on I learned my lesson and watched carefully for cracks.
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done. luckily the surface was all, no internal fatigue/cracks. did moderate filing & polishing on both sides. i can sleep now.
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That's a nice, clean job of it
DD
DD
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Funny how threads about the same topic sometimes pop up at the same time:
https://groups.google.com/forum/#!to...es/b3DsZL4XQiU
and a link from Jim Merz's reply:
https://forum.cyclinguk.org/viewtopic.php?f=5&t=121671
Note how the crack starts on the high side of the crank downstroke where all the force would be down and out due to the pedal and crank arm acting as a lever. Also, in this picture, does it look a little like the web was filed a bit?
Pretty sobering!
https://groups.google.com/forum/#!to...es/b3DsZL4XQiU
and a link from Jim Merz's reply:
https://forum.cyclinguk.org/viewtopic.php?f=5&t=121671
Note how the crack starts on the high side of the crank downstroke where all the force would be down and out due to the pedal and crank arm acting as a lever. Also, in this picture, does it look a little like the web was filed a bit?
Pretty sobering!
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Last edited by mech986; 07-28-20 at 12:46 AM.
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It looks like you've resolved your issue; however double check for micro-cracks by stressing the crank while examining under bright light and magnification.
I was rudely introduced to the road a few years back when I broke a crank so I routinely check my vintage cranks using this method. If there are cracks, you'll see them.
I was rudely introduced to the road a few years back when I broke a crank so I routinely check my vintage cranks using this method. If there are cracks, you'll see them.
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Note that the beach marks show that the crack had extended approximately 40% of the way across the crank shaft, and yet someone continued to ride it. It would have been easily visible, yet it was ignored. +1 Inspect cranks regularly with light and magnification.Not unusual for used campy record cranks from BITD to have really big miles on them.
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2 hours before this posted I bought a really clean Super Record crankset off Ebay. After reading this I went back and took a REALLY close look at the pictures and there appears to be a small crack. 😮😕 Has anyone tried drilling a hole at the end of the crack then grinding it out to a V shape and TIG welding it? I have done this with great success on other aluminum items. It would only take a "tack" weld to fill the V so the heat affected zone would be quite small. I would leave the TIG weld to a friend, he has a custom metal fabrication shop and does this type of repair on auto and motorcycle components often. He's a much better welder than me.
Here's a picture from the auction, it's not the best. The area in question is circled in red, I can't tell if it's just a line, a crack or dirt. I guess I'll know for sure when it gets here.
Here's a picture from the auction, it's not the best. The area in question is circled in red, I can't tell if it's just a line, a crack or dirt. I guess I'll know for sure when it gets here.
Last edited by Murray Missile; 07-28-20 at 04:43 PM. Reason: Photo added.
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double checked it with a loupe under a blinding light. currently no more visible crack or sign. and will check often to see if there's any.
excited to see if the filing really has done any 'practical' effect.
for whom might have wondered, i've used:
1. gentle hand-filing with a hobby size round file, about 1/16 ⌀
2. finishing with 3M320F block. peel-off-cut a small piece like a blanket, taped to a small rod. applied with the hand drill with low-speed. very meditating it was.
wanted to do it delicate way, have seen horrendous jobs on the web, that actually ruined the nice connecting outline from the arm the the spider.
happy with the output, for now.
thanks for all the insights & advice.
excited to see if the filing really has done any 'practical' effect.
for whom might have wondered, i've used:
1. gentle hand-filing with a hobby size round file, about 1/16 ⌀
2. finishing with 3M320F block. peel-off-cut a small piece like a blanket, taped to a small rod. applied with the hand drill with low-speed. very meditating it was.
wanted to do it delicate way, have seen horrendous jobs on the web, that actually ruined the nice connecting outline from the arm the the spider.
happy with the output, for now.
thanks for all the insights & advice.
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#14
car dodger
Would like to see more pics of filed / fixed cranks...
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#17
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Nice to see how far up the arm you went, helpful!
Will try to post pics of mine tomorrow.
Will try to post pics of mine tomorrow.
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"I've consulted my sources and I'm pretty sure your derailleur does not exist"
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1980 Mclean/Silk Hope Sport Touring
1983 Bianchi pista
1976 Fuji Feather track
1979 raleigh track
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Yep, I had a bounty last year with a beautiful frame and components, including an SR Royal super light crank. Sure enough, there was a hairline, and when I started filing, I couldn't find the end of the crack. Though I may re-purpose the chainrings at some point, the drive side crank is wall art.
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Note that the beach marks show that the crack had extended approximately 40% of the way across the crank shaft, and yet someone continued to ride it. It would have been easily visible, yet it was ignored. +1 Inspect cranks regularly with light and magnification.Not unusual for used campy record cranks from BITD to have really big miles on them.
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#20
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Oh, thanks for that info. That makes more sense. I had never seen a campy crank with one of those spider starter cracks that had completely failed in real life.
#21
car dodger
Here's a campy triple currently on my Mclean, that I filed a year or so ago.
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"I've consulted my sources and I'm pretty sure your derailleur does not exist"
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and here is a pista crank on my raleigh track that I filed a few years ago. It has held up fine but I don't ride the bike that much.
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"I've consulted my sources and I'm pretty sure your derailleur does not exist"
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1980 Mclean/Silk Hope Sport Touring
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1976 Fuji Feather track
1979 raleigh track
"I've consulted my sources and I'm pretty sure your derailleur does not exist"
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Nice job of polishing out the hairline orangeology . I worked in failure analysis of steel, in the construction industry (quality engineer,) for 30+ years, you might want to do a "poor man's" Magnaflux test to the spider, for peace of mind. Soak the spider liberally with WD-40, or even some thin spray lubricant, then wipe it dry after letting it sit for a bit. Once cleaned off, apply some baby powder to the entire piece, then blow it clean. If there is a crack anywhere you'll see it where the soaked in liquid has absorbed the powder.
Bill
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Nice job of polishing out the hairline orangeology . I worked in failure analysis of steel, in the construction industry (quality engineer,) for 30+ years, you might want to do a "poor man's" Magnaflux test to the spider, for peace of mind. Soak the spider liberally with WD-40, or even some thin spray lubricant, then wipe it dry after letting it sit for a bit. Once cleaned off, apply some baby powder to the entire piece, then blow it clean. If there is a crack anywhere you'll see it where the soaked in liquid has absorbed the powder.
Bill
Bill
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My Super Record crankset arrived, no cracks, it was just a shadow in the photo. It's a beautiful thing!
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