tiger1964 

I've read on-line about Campy cranks breaking if there is marking on the arm from toe straps rubbing the arm. Is there a way to determine acceptable versus unacceptable on used cranks? In my other topic on the Palo Alto to Masi conversion, I've found I need to get new cranks really soon, and either a WTB here or eBay. Don't want to spend $$$ and break off a crank. NOS could get even more $$$$; I don't need "pristine" but nice, and certainly not failure-prone.

CliffordK

What model of crankset are you talking about?

I've got pretty deep toe strap rub on one Nuovo Record / Strada crankset. The old cranksets were SOLID. One thing about toe strap rub is that it tends to be very smooth. And, I presume the cranksets can take a lot of it.

Looking at a few photos of cracked Campy cranks on the WWW. There appear to be at least 2 cranks with machined/drilled spiders that failed. It may seem like a fun idea to drill... but not if it leaves one walking (or laying on the ground).

Fixed Gear Blog: Broken Campagnolo Cranks
https://www.bikeforums.net/5001246-post16.html

Skidding fixies may also create stresses not normally seen with cranksets.

There is one Chorus crankset that appears to have had a deep OLD crack going halfway through the crank, and eventually causing failure.

https://imgur.com/r/Justridingalong/RB0VI

And one NR crank that failed near the spider.

There is some materials analysis here along with two failed Campagnolo Strada Cranksets.

https://pardo.net/bike/pic/fail-009/000.html

Again, the issue appears to be the propagation of cracks, and not rub.

There are a lot of vintage Campagnolo cranksets out on the road.



Deep toestrap rub may not be a cause of failure, but could be indicative of long hard use of the crankset (which would be the risk factor of fatigue).

Spaghetti Legs 

I’ve never heard of that problem before. The only failure issue I’ve heard of with Campy Record/Super Record cranks, and it is rare, is on the inside of the spider and the problem was addressed with a design change somewhere along the way (late 70’s? Just a guess).

cudak888 

For all the hullabaloo over Record cranks cracking at the sharp transition between the spider and the arm (yes, they do crack, and chances are your set is too). I can't recall anyone here ever encountering a failure due to that one specific crack.

The post-CPSC cranks do not smooth the stress riser area; they're as sharp as the post-CPSC versions. There's nothing obvious upon visual inspection to suggest any improvements were made on the later cranks.

-Kurt

qcpmsame 

Owned both Pre- and Post- CPSC Record spider/arms and never had any issues, not have I had any trouble with some rub marks from straps propagating/starting a crack in the arm, left or right. I'd be interested in learning if this has or was ever a problem, some of the Campagnolo cognoscenti need to enlighten us on this one, please.

I think you'd be safe with pretty much any Record arm/spider you find here, and just do your due diligence on eBay.

Bill

Last ride 76 

Urban legends propagate ... faster than the cracks in a campy crank.
As has been noted in posts above, the Record drive side crank arms sometimes developed stress cracks that could, if left unchecked, ocassionally lead to failure... Here is a link to a previous thread.https://www.bikeforums.net/general-cycling-discussion/830567-componant-failures-maybe-we-should-adding-weight-key-components.htm
Interesting photos, but as mentioned elsewhere, rounding out the surface, to remove the crack and stress risers...https://www.bikeforums.net/classic-v...relieving.html.

This was the occasional problem, along with the solution... toe strap rub - nice smooth curve, would have to get very deep before becoming a significant issue.

What thread searches are for.
Eric

repechage

The very very late Production cranks where the machined tapered flute was dropped have on the backside reasonably elaborate milling that beefs up the problem area. So, Campagnolo did know, just took a long time to address it and or free up (purchase?) a CNC mill to effect the change.

The very early Record cranks addressed what would become the problem area also, they are machined away, there is a “trench” a slot, that isolates the arm from the spyder.

Way back we had a few broken cranks come through the shop, Toe strap rub always was present at the break about 30 mm above the pedal eye. Campagnolo mad good on those, they DID suggest not setting the toe clips it a way where the strap or shoe would abrade the crank.
interestingly a shop employee had a set of cranks so worn that the wear was to the base of the fluting and on one side beyond. He replaced the crank arms after a customer brought his fractures crank arm in for warranty.

T-Mar

I've never seen a failure attributable to toe strap rub but I have seen several Camapagnolo crankarm failures. In addition to failures at the noted spider stress riser, I've personally broken a non-drive side (Nuovo) Record crankarm.

Last ride 76 

You brute. Seriously - you brute. That took some doing. I know it happened, but I knew some real beasts, who never managed it. Lots of miles, prior impact, material flaw, or none of the above? Hope you were ok, I can see very bad things happening as a result.

79pmooney

I regularly wore Sugino cranks to 25-33% from toeclips and winter boot wear on my commuters. Never had one break. Now I make stops held in place by the inboard rattrap screws to keep toestrap and shoe off the pedal. (Wearing out 175mm Sugino 75s is NOT acceptable!)

79pmooney

I rode past two broken drive side NR cranks in races. I was on the wheel of both. It was exciting. Especially the second where I had to thread the needle between him and the curb coming out of a criterium corner. Both broke across the pedal threads.

I did the same drive side pedal thread breakage of an Avocet (Ofmega?) crank.

Ben