Campagnolo NR/SR cranksets - Has anyone on C&V actually broken one?
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I haven't done it but in my racing days I was twice on the wheel of a Campy (probably NR) crankset rider when the right crank broke. Both riders crashed. I missed both. This was in the late '70s.
Those cranks were well made, but - many have led hard lives, they have cut threads (both I saw broke at the pedal) and they are aluminum. None of them are new.
Ben
Those cranks were well made, but - many have led hard lives, they have cut threads (both I saw broke at the pedal) and they are aluminum. None of them are new.
Ben
#28
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Never broke a crank, never seen anyone else break a crank,
European racers tend to be a bit smaller, so probably less crank stress, plus they have technique, always spinning, and they get a new bike every year, or every month if you are Sean Kelly pedaling a swing set, Although now that I think about it, they might be smaller but have 10 times the horse power that I do.
This thread is making me nervous, Nervar steel cranks are not that heavy, maybe it is time to go retro.
No, those cotter pins suck. Filed too many of those. Remember, they would sell you a blank for 35 cents and you would have to file it to fit your particular crank? Then the nut would strip because the pin was too big so you tried to wedge it deeper by using brute force on the 10-28 nut. Do not miss those days. Especially after a bad pin job would start the crank to jerk around on the spindle at the top and bottom of each stroke. So you got out the hammer and put a mushroom on top of the pin. Then when the crank slop got too bad and it was time to do another pin, you would hammer the pin so hard that it would bend and get stuck inside the crank, then requiring a center punch which usually resulted in a bruised thumb from a hammer slip. So you farm the job out to your big brother, he grabs the Lincoln stick welder and proceeds to set the bottom bracket on fire.
Broke a few chains, has the same effect as breaking a crank.
One time i was sprinting through a yellow light at a busy intersection. next thing you know i hit the ground like a sack of dead flour. I am laying there and the light flips green, and drivers start honking at me to get out of the way, even after having witnessed the crash. When I did not move they started driving around me on both sides. Luckily one kind soul stopped long enough for me to scamper off and lick my wounds.
But that is typical of Bay Area drivers who are dying to get home to those two martinis.
Anybody ever break a Suntour Superbe Pro crank? They look pretty stout.
European racers tend to be a bit smaller, so probably less crank stress, plus they have technique, always spinning, and they get a new bike every year, or every month if you are Sean Kelly pedaling a swing set, Although now that I think about it, they might be smaller but have 10 times the horse power that I do.
This thread is making me nervous, Nervar steel cranks are not that heavy, maybe it is time to go retro.
No, those cotter pins suck. Filed too many of those. Remember, they would sell you a blank for 35 cents and you would have to file it to fit your particular crank? Then the nut would strip because the pin was too big so you tried to wedge it deeper by using brute force on the 10-28 nut. Do not miss those days. Especially after a bad pin job would start the crank to jerk around on the spindle at the top and bottom of each stroke. So you got out the hammer and put a mushroom on top of the pin. Then when the crank slop got too bad and it was time to do another pin, you would hammer the pin so hard that it would bend and get stuck inside the crank, then requiring a center punch which usually resulted in a bruised thumb from a hammer slip. So you farm the job out to your big brother, he grabs the Lincoln stick welder and proceeds to set the bottom bracket on fire.
Broke a few chains, has the same effect as breaking a crank.
One time i was sprinting through a yellow light at a busy intersection. next thing you know i hit the ground like a sack of dead flour. I am laying there and the light flips green, and drivers start honking at me to get out of the way, even after having witnessed the crash. When I did not move they started driving around me on both sides. Luckily one kind soul stopped long enough for me to scamper off and lick my wounds.
But that is typical of Bay Area drivers who are dying to get home to those two martinis.
Anybody ever break a Suntour Superbe Pro crank? They look pretty stout.
Last edited by cjenrick; 09-23-20 at 12:04 AM.
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I have a spider crack crank, NR. It is on my least used bike. I ride it but I am not doing 400/week either.
If we are going to get specific, should we include date codes and perhaps length?
If we are going to get specific, should we include date codes and perhaps length?
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I'm still not buying the notion that they were worse than other cranks from the time period. Stronglight 93/105 didn't crack, but the soft alloy caused other issues. AFAIK Brandt went directly from steel cottered to Campy NR/SR, not riding anything else until eventually switching to 7400. Like pretty much every one else. It's not like there was some big variety of choices BITD in pro level cranksets. Different time. He told me he preferred the old steel cranks. May have been an off the cuff comment.
Aluminum fatigues with enough cycles. I had worse luck with other brands.
Aluminum fatigues with enough cycles. I had worse luck with other brands.
To your overall point, Ric Hjertberg's take has always stuck with me:
Campag cranks were the vast majority of failures because they saw the really serious miles. Victims were sure not to stray from Campag for fear of even worse experiences. The more of their cranks you broke the more you recommended to others like yourself to use nothing else.
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Last edited by ThermionicScott; 09-23-20 at 11:21 AM.
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#33
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Nope. They all break. ^^^ (referring to sugino et al)
You see more broken campy because that's what 99% of racers used.
You see more broken campy because that's what 99% of racers used.
Last edited by Salamandrine; 09-23-20 at 11:31 AM.
#34
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FWIW, my favorite modern cranks is the current version of the Sugino Mighty Tour. Made from 200x alloy instead of 60xx. Much stronger. Way more meat around the pedal eye than vintage cranks. Not cheap, and hard to find. If I was just going on looks I'd get a Herse reissue, but my past experience makes me pretty sure I'd snap it eventually.
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Ah, found it!
https://yarchive.net/bike/cranks.html
I shoulda just found the link in the beginning.
Originally Posted by Jobst Brandt
Besides, I can vouch for
the failings of C-Record Campagnolo cranks. My only set failed both
cranks at the pedal in less than 200 miles. That occurred before I go
around to the first inspection. I stopped that right there and
switched to Dura Ace with a modicum of success.
the failings of C-Record Campagnolo cranks. My only set failed both
cranks at the pedal in less than 200 miles. That occurred before I go
around to the first inspection. I stopped that right there and
switched to Dura Ace with a modicum of success.
I shoulda just found the link in the beginning.
#36
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There you go. I guess C Record was not an improvement then....
Does anyone know if the Dura Ace 7400 cranks were 2000 series aluminum? That would tend to explain the better durability vs NR/SR. Also, it's a 20+ years newer design with less stress risers. That helps too.
I suspect much of this comes down to 6000 series vs 2000 series.
I still think a modern steel crank would be superior, something like the old Bullseyes, but a bit more refined. I was convinced years ago. I hear that carbon stuff is OK though.
Does anyone know if the Dura Ace 7400 cranks were 2000 series aluminum? That would tend to explain the better durability vs NR/SR. Also, it's a 20+ years newer design with less stress risers. That helps too.
I suspect much of this comes down to 6000 series vs 2000 series.
I still think a modern steel crank would be superior, something like the old Bullseyes, but a bit more refined. I was convinced years ago. I hear that carbon stuff is OK though.
#37
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Here is a quote from a forging industry website that may be of interest.....Does anyone know what alloy is generally used for forged cranksets?
"The strength properties of aluminum alloys are affected by alloy composition, forging process variables and the final heat treatment. Corrosion resistance is affected primarily by alloy composition and the final aging cycle. For example, the 2xxx series, with significant amounts of copper, are generally more prone to atmospheric corrosion, pitting, stress corrosion and galvanic reactions than are zinc-magnesium 7xxx alloys with very low levels of copper.
Aluminum forging alloys 2xxx and 7xxx are used extensively in aerospace applications and airframe structures, due to their favorable high fatigue strength and low density. The 2xxx and 6xxx grades are selected for automotive applications, with the 6xxx grades specified where superior resistance to corrosion is required."
"The strength properties of aluminum alloys are affected by alloy composition, forging process variables and the final heat treatment. Corrosion resistance is affected primarily by alloy composition and the final aging cycle. For example, the 2xxx series, with significant amounts of copper, are generally more prone to atmospheric corrosion, pitting, stress corrosion and galvanic reactions than are zinc-magnesium 7xxx alloys with very low levels of copper.
Aluminum forging alloys 2xxx and 7xxx are used extensively in aerospace applications and airframe structures, due to their favorable high fatigue strength and low density. The 2xxx and 6xxx grades are selected for automotive applications, with the 6xxx grades specified where superior resistance to corrosion is required."
#38
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I'm amazed that your collar bone has undergone such wear and tear!
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Not sure if you can get it w/o buying a frame along with it (not that this would be a bad thing...)
Steve in Peoria
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Here's my question. Why hasn't there been a more serious, mainstream approach to steel cranks in the world of road bikes?
In the BMX world, Odyssey Thunderbolts and Profile cranks are hugely successful, and very strong.
Claimed weight of a set of those Thunderbolts is 1.76 lbs. Claimed weight of a Dura Ace 9100 hollowtech set is 621 grams, or 1.369 lbs.
BMX cranks are made to take much more abuse, so I'd bet that weight could be brought down to nearly match top level road equipment.
What am I missing?
In the BMX world, Odyssey Thunderbolts and Profile cranks are hugely successful, and very strong.
Claimed weight of a set of those Thunderbolts is 1.76 lbs. Claimed weight of a Dura Ace 9100 hollowtech set is 621 grams, or 1.369 lbs.
BMX cranks are made to take much more abuse, so I'd bet that weight could be brought down to nearly match top level road equipment.
What am I missing?
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@steelbikeguy, that crankset is gorgeous! Love it!
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There Brandt said that a Campy crank always lasted him less than a year. That's some serious pedaling. He claimed he was not unusually strong, but we know that's not true. He was strong, he rode many miles a year, very vigorously, and he was about 6'5" tall with long legs, all factors contributing to crank failure. This thread has changed my view. I accept that the cranks that got the most hard miles failed the most, and it may not have been more deeply flawed than others. But why did the Dura Ace cranks work so well for Brandt? Did they have a secret?
If he had developed the collets during his NR/SR days, I wonder if he would have stuck with those...
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#45
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@BFisher, excellent question. How many people would that appeal to? I’m not strong enough to need such a strong crank. And bike people will be skeptical about steel now that we’ve had alu cranks for so long. I’d guess it’s too small a niche market. But I’m only guessing.
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@BFisher, excellent question. How many people would that appeal to? I’m not strong enough to need such a strong crank. And bike people will be skeptical about steel now that we’ve had alu cranks for so long. I’d guess it’s too small a niche market. But I’m only guessing.
#47
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Campagnolo made these for a few years in the early seventies. Personally, I think they are lovely to look at but there is a ~300 gram weight penalty vs. Nuovo Record.
Campagnolo Sport Crankset mod. 3320
Campagnolo Sport Crankset mod. 3320
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#49
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How quickly a thread finds its way to the third or fourth page on a lively forum. But since I opened this can of worms most recently I thought I should offer something in the way of conclusion.
I borrowed this graph that I found by googling "aluminum fatigue". There were lots to choose from but since this illustrated the difference between aluminum and steel, I thought it might help us choose a fatigue life value.
If we can agree that steel cranksets DON'T break then I think we can assume that the aluminum crank failures occur somewhere after the knee in the fatique curve for steel - around a million cycles. There are exceptions to that for sure - consider the following table (from the same source):
This would indicate that someone who really rides their bike really hard (Jobst Brandt, young, strong racers riding at 100% effort much of the time) could break a crank is as few as 1000 cycles above the threshold of strain required to count as a "fatigue cycle". That would explain why guys like Jobst would have to replace a crankarm in as little as a year or two while some of us are (a bit nervously in my case) riding the same parts more than 45 years after they were first put into service.
So, what remains unknown is to quantify what counts as "above the threshold to count as a fatigue cycle". If that level of strain is never exceeded the crankset will NEVER fail. If we use the knee of the steel curve and say we have a million cycles to breakage, that is still quite a bit of use if, say, you have to be honking out of the saddle in order to reach that level of stress. Realistically, as a guy in his late sixties, I'm going to quantify this "threshold" as somewhere between where knees start to hurt and when a hip breaks - in other words, biofeedback amongst us old-timers will ensure that the cranksets do not fail and we don't need to worry much about them. Those that are still young, strong and have high levels of stamina - check them cranks often for cracks!
I borrowed this graph that I found by googling "aluminum fatigue". There were lots to choose from but since this illustrated the difference between aluminum and steel, I thought it might help us choose a fatigue life value.
If we can agree that steel cranksets DON'T break then I think we can assume that the aluminum crank failures occur somewhere after the knee in the fatique curve for steel - around a million cycles. There are exceptions to that for sure - consider the following table (from the same source):
This would indicate that someone who really rides their bike really hard (Jobst Brandt, young, strong racers riding at 100% effort much of the time) could break a crank is as few as 1000 cycles above the threshold of strain required to count as a "fatigue cycle". That would explain why guys like Jobst would have to replace a crankarm in as little as a year or two while some of us are (a bit nervously in my case) riding the same parts more than 45 years after they were first put into service.
So, what remains unknown is to quantify what counts as "above the threshold to count as a fatigue cycle". If that level of strain is never exceeded the crankset will NEVER fail. If we use the knee of the steel curve and say we have a million cycles to breakage, that is still quite a bit of use if, say, you have to be honking out of the saddle in order to reach that level of stress. Realistically, as a guy in his late sixties, I'm going to quantify this "threshold" as somewhere between where knees start to hurt and when a hip breaks - in other words, biofeedback amongst us old-timers will ensure that the cranksets do not fail and we don't need to worry much about them. Those that are still young, strong and have high levels of stamina - check them cranks often for cracks!
#50
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@daka, thank you for that perspective. I'm 59, and I took a short ride with my daughter today. She's 31 and muscular though not a very seasoned cyclist. She said, "Let's go as fast as we can," so I had no time to prepare. We sprinted until we didn't want to any more. It was very short, and I almost lost my lead. I felt very weak compared with years past. I'm still good on uphills but always have been terrible on the flats.
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