+1....if it walks like a duck............

would foot position make any difference??...if a rider was consistently on the outer edge of the pedals; would the highest stress point move outwards too? I can imagine a rider with an overly wide foot might tend to put pressure somewhere other than the strongest part of the spindle........and if they were a large person...?

Sorry for the 'twinge'. When I said 'if I can' I assumed 'safely' would be understood.

I had to take some motorcycle heads to a machine shop for new valves and seats yesterday (coincidentally, because BMW used the wrong material for the seats back in 1981 to 1983) and as the Peugeot is my only bike with a saddlebag I went on that. I found was that I was unwilling to get off the saddle so it's obvious that I have lost confidence in the pedals on that bike, the right pedal is the pair of the one that broke the other day and the replacement left pedal is one from the same lot of 2 NOS pairs that the other pair of broken ones came from.

The first 2 breakages were within a couple of weeks of fitting them to my fixed-gear Chesini Pista. The Peugeot has seen very little use in the 2 and a half years since I built it - maybe a total of 100 miles. However, the Lyotard 460D pedals on my Dawes were well-worn when I started using them around 3 years ago and since then have seen regular and hard use. The ones on my Hetchins MO likewise have see a lot of regular, hard use. I won't know how I feel about the Dawes and Hetchins pedals until I ride the bikes but I think they are probably okay. These pedals have been used by serious cyclists since the 1930s so they can't all be bad.

Thanks for the tip about bike shops.

Well, my girlfriend was quick with the suggestion that I was too heavy for the pedals. I weigh 91 kgs (201 US lbs) and that obviously has something to do with the stress on the pedals. Also, my riding style involves quite a lot of sudden, quick bursts of acceleration as I ride mostly in Tokyo and believe in keeping up with the traffic.

It isn't your weight.

It isn't your riding style.

I weigh more than you. I rode and continue to ride aggressively. I've never broken a spindle on any pedal. You likely have defective pedals there. It wasn't likely you. I was likely just a matter of time, that is, they have inadequate fatigue life due to the manufacture and/or metallurgy.

After 40 years experience as a metallurgical engineer maybe I can add some info on these failures. One of the key factors in hydrogen embrittlement failure is sustained tensile stress. The generally accepted theory is that monatomic hydrogen atoms dissolved in the steel matrix (classically from plating operations but not always) diffuse towards the larger interstitial spaces in high tensile stress areas and help precipitate brittle behavior of the metal at the stress raiser or crack tip. Thus hydrogen embrittlement is an issue in parts like spokes, QR shafts, and various high stress bolts where there is a high sustained tensile stress. Not so much in parts subjected to cyclic stresses as there is not enough time for the hydrogen diffusion during each tension cycle. There is also a tensile stress threshold below which hydrogen embrittlement is unlikely in steel. Without looking it up, it’s around 160,000 psi which is why it’s almost unheard of in parts with a yield strength (or hardness of 40 Rockwell C) or less; the parts yield and thus do not see high sustained tensile stress. So lots of SAE grade 8 bolt hydrogen embrittlement issues, not so much a problem with SAE grade 5 bolts.

The fracture faces show signs of reverse bending fatigue; note that the fracture features are roughly symmetrical about a mid diameter line. If Dawes-man were to fit the broken stubs back into the same cranks and the mid diameter line was roughly parallel to the ground when the cranks are also parallel to the ground (maximum bending stress position) that would tend to confirm my hypothesis. Bonus points if the “wider” part of the fracture is “up”.

Auchencrow is not wrong per se, but is misinterpreting the evidence. Most (less than half in my experience) fatigue fractures do not display obvious fatigue striations (also known as “beach marks”) as in his (please excuse if you, Auchencrow, are other than conventionally male) photo of a classic bidirectional bending fatigue fracture @ 1/23/11 12:16 am so clearly shows. Many fatigue striations don’t show short of scanning electron microscope examination and even that is not a sure bet. His photos at 1/23/11, 12:35 am are clearly unidirectional bending brittle failures with the fracture initiations at 6:00 O’clock as indicated by the overall direction of the river (or “chevron”) marks. Those marks tend to “V” out from the initiation site. But hydrogen embrittlement fractures being typically brittle does not equal brittle failures being typically hydrogen embrittlement.

If it were my pedals and nuts, I’d
1) Polish the pedal shafts in the area where the fractures are occurring to a 600 grit or better finish to minimize the stress risers and make subsequent inspections easier. Various abrasive papers and cloths make that reasonable even if you have to use them “shoe shine” method. Better if you can run the final polish marks parallel to the spindle rather than circumferential.
2) I’d tear down the pedals every few hundred to a thousand hours of riding (if you ride a couple plus hours a day that’s about once a year) and seriously eye ball the suspect area for cracks. Dye penetrant or magnetic particle inspection would be a bonus but is probably overkill if you’re diligent about looking for cracking. Less so after the first couple of thousand hours. There is a “fatigue limit” for steel parts. Barring impacts, steel parts (does not apply to aluminum ect.) subjected to ten to the seven cycles (10 million cycles) without failure are unlikely to ever fail. 1000 hours of cycling at 100 rpm equals 6 million cycles.

MikeX, thank you! I am fascinated by your answer.

This is a photo of the stub in another Campagnolo crank. I can take another in the same crank tomorrow but if their thread cutters are used methodically, the photo would support what you suggest, I think.
[IMG]
IMG_5322 by Dawes-man, on Flickr[/IMG]

I remember a friend saying that racing engine con rods are often polished for strength. I've just done that using an electric drill at slow speed and 400, then 600, then 1000 grit abrasive paper wrapped around the spindle and held by hand. I finished it off with longitudinal polishing with 1000 grit. This is the result.

[IMG]
IMG_5325 by Dawes-man, on Flickr[/IMG]

[IMG]
IMG_5324 by Dawes-man, on Flickr[/IMG]

[IMG]
IMG_5323 by Dawes-man, on Flickr[/IMG]

I noticed while polishing around that there seemed to be faint longitudinal ridges in the metal. Polished, you can see faint circumferential nicks and I'm wondering of I should polish until they are all gone.

I too am a fan of the 460d pedal and have them on several of my early-mid sixties road bikes.
Fortunately I am a recreational rider and almost never ride out of the saddle.

I am also a fan of the MKS Sylvan touring pedal and use them exclusively on my later bikes(eighties & nineties vintage).

Because most of the 460d pedals I could find were French threaded or had shorter threaded sections meant for steel cranks, I did an experimental transplant of MKS Sylvan touring spindles into 460d pedals. I ran into some complication. It's been long enough now that I don't remember what the complication was but I was able to overcome it without drastic measures. I've never done it again so it must have been enough work to dissuade me, but judging from the price of those vintage British pedals you posted the link to, it would probably be well worth the effort.

Many thanks for this info. I'd given up thinking anyone might have tried it.

I do think this is true, however, I'm not sure about how valid it is if you have manufacturing defects. After all, there is a fatigue limit. The spindle surface is brittle. As few as one high stress cycle could cause a surface crack to propogate and invalidate the prior fatigue life history.

Note, in Dawes-Man's bottom-most photo, there is a rather large "feature" which he has not yet polished out. In fact, the polishing has served to highlight it. It is on the right side of the shaft, almost dead center in the photo. Note also, there is a circumferential groove just slightly above that. In a brittle, case-hardened part, either or both of these could be a site at which a crack develops from fatigue.

I do like the idea of polishing the surface to minimize defects. This is the type of manufacturing processing that raises the price of the parts, so it wasn't done.

Do we know if these spindles were machined or forged (or both)?

Shot peening is also used to effectively strengthen parts. It induces a residual compressive stress in the surface, so the effective tensile strength is higher than before peening. Again, this costs money, so it wasn't done.

If you're enough of a fanatic to ride 1950's bikes, then of course you're not going to want to use modern pedals on them. Berthet's were around back then, and there were several other older Lyotard models, although maybe they used the same spindles... I've seen British pedals like Barelli and Brampton sell on Ebay for reasonable amounts. I got a set of NOS 460's for my Motobecane, they have straight rather than serrated cage edges, which I have not seen elsewhere. I haven't ridden them much yet, and now I'm kind of wondering if I should.

Just checked my pedals, and they're an all-steel version of the 460. Probably the same spindles, though.

Intresting thread for me to follow, but at least there have been no other 460D's reported as breaking.

I love this style of pedal, and use atom 440's on many of my city bikes.

Thanks MikeX -- It is good to hear from someone who IS trained in metallurgy. I’ve learned a few things – Like why the HE failures I’ve seen occurred mostly on plated Gr8 fasteners under constant load, and why these brittle failures are different.

Word is that Lyotard used metal from some rejected Mirage fighter landing gear axle steel stock that JP Routens were milling for the French government. Little that Lyotard know that the scrap steel they bought from JPR were purposely overheated for heat treatment error caused failure tests. The warehouse manager at JPR (known as "Le Bastarde" to JPR workers at that time) who sold the bad steel stock to Lyortard through the "back door" figured the new pedal axles should last long enough that he will be long gone before anyone knew what was going on with the pedals.
He lived on the profits from the bad metal sales to Lyotard in comfort at the Costa Del Sol Spanish Riviera vacation area till his demise one summer in the 80's from a massive heart attack he suffered while watching "The Badger" get beat by the pesky American in the TDF, named Greg!
Ironically, the police who investigated the sudden death, found a Peugeot bike parked in his garage..........with one Lyotard rat trap pedal mysteriously bent downwards...... a possible clue to the timing of the man's heart failure??

Chombi

All,

Nothing to see when I took the L- apart. But these are the 136R pedals, not the 460's. Are these ( 136 ) a different animal?

Dawes-man, 115 race weight but that was before the heart went on strike, now 150lbs. But still active !

3SS

It seems that MKS spindles can break too:
https://www.fixedgearfever.com/module...ewtopic&t=8073

Dawes-Man, in your original post you said they broke during low speed. Low speed does not mean low stress. The link's break occurred at low speed but high torque because he was trying to accelerate when it broke.

The cumulative fatigue from "10 million" low stress cycles can be completely overwhelmed if you give it a few high stress cycles (such as when you are trying to accelerate). Add in a few manufacturing defects and use a brittle material and you get a cracked spindle.

Is Chombi pulling our collective legs, or is that a real story?

This thread is making me want to disassemble and inspect my old pedals.

Yes, I have a pair of Berthets on my Hetchins Nulli and I have just bought a pair of Brampton B8s from Hilary Stone's new site for what I think is a reasonable £49. I've just been offered a very good pair of Conloy Asp platform pedals (about 2/5ths of the way along the strip here - https://www.speedplay.com/index.cfm?f...almuseum.quill ) by a dealer friend in the UK for £130, which is more than I'm used to paying for pedals. As the friend says, 'Pedals and saddles are the first things to wear out, hence they are expensive.' I'm undecided...

The Berthet spindles are different from the 460D's, being just over half an inch shorter. Doesn't mean they can't break, though. These Berthets are from the 50s, though, and I imagine more money was spent on materials back then. The 460Ds that have broken have all been much later, from the 70s and 80s, before Lyotard stopped trading.

You are completely right about not wanting to use modern pedals on my 50s bikes. Part of the joy of riding such machines for me is the fact that they are the same age, or older, than me and that they are still going strong. Using the 460Ds is actually cheating a bit as that version of the pedal came out in the early 70s, but they look the part. My fault for being a cheapskate.

Yes, I'm wondering whether, had I had a close look at the spindle before it snapped, would I have seen a crack? And if so, how long before it failed would the the crack have appeared? Or would the crack have appeared just a few revolutions of the crack before it broke completely?

I like this idea too! It's a way you can easily add quality to components. I also like MikeX's suggestion of periodically dismantling pedals and inspecting the spindle surfaces.

On your observations of the marks on the lowest photo, the mark halfway up the spindle on the right looks to me like something has struck it as you would a tree you were felling, from above leaving an elongated triangle and ending with a slight ledge that you can just feel with a finger nail, about 0.2mm deep I'm wondering whether to polish it out but am worried about reducing the diameter of the spindle.

[IMG]
IMG_5330 by Dawes-man, on Flickr[/IMG]

Looking closely at the spindle, pig-iron springs to mind. I remember my primary school teacher telling us how it was made with strands of iron bundled together. The spindle has strands running longways, which I first noticed from the slight pulsating feeling in my fingers holding the abrasive paper when I polished it. They are plainly visible in the following photo and they run the length:

[IMG]
IMG_5327 by Dawes-man, on Flickr[/IMG]

Given what I have learnt in this thread about circumferential surface marks facilitating failure, it seems to me that these longitudinal strands serve to strengthen the spindle. Didn't work

The 460D was the pedal of choice for Cyclocrossers , pre spud, and Dieter Runkle,
because they were cheap enough to be disposable ..

Thing was, I wasn't accelerating or pedaling hard when they broke. I had pedaled hard on them on several occasions before.

Definitely the former as the guy's name in French would be Bātard and it doesn't have the connotation that it has in English.

Me too! And I think it has to be a good thing. All these years I've pretty much taken pedals for granted...

Are you sure he wasn't known as 'La Pedale'? Now THAT would be a joke for the connoisseur

Some, maybe most, of those longitudinal marks/striations look to me to be tooling marks. The deep ones are probably from a collet chuck used to hold the part while making the threads.

In my experience, large grained, columnar structures are almost always bad news.


P.S. - I forgot to say this earlier - many thanks to MikeX. That was a great post. I'm not disagreeing at all, I'm just trying to discuss this further and learn more about it. Thanks, MikeX.

the pedal stroke that caused the failure doesn't have to be much because the crack had progressed to the point that it didn't take much to break it in half.