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Replace your pedals

Sept. 15, 2015, 8:13 a.m.
Posts: 19
Joined: Nov. 20, 2002

I prefer to forget about stuff like that. Biking is expensive enough without replacing perfectly good parts out of unwarranted fear of one off failure.

this. not saying this is the case here but that's the price you pay when pushing limits on weight.

http://www.epiccyclist.com/

Sept. 15, 2015, 9:05 a.m.
Posts: 5635
Joined: Oct. 28, 2008

Ruh roh. Should I take my scarabs apart and look at them? How often are these pedals supposed to be regreased etc? I've never even touched mine as far as maintenance goes.

Wrong. Always.

Sept. 15, 2015, 10:39 a.m.
Posts: 7306
Joined: Nov. 20, 2002

I don't think so. The smooth part is probably a fatigue crack. A closer inspection will probably reveal beaching marks. Once the crack reached what looks like 1/3 of the way through the axle was no longer strong enough and failed. The rough part is brittle fracture. This type of failure happened suddenly across the remaining pedal axle along the grain boundaries (which is why it looks like sugar crystals).

My guess is that there was a small flaw in the axle that created a stress riser. This initiated a crack which propagated across the axle under repeated loading. In other words, a very classic fatigue failure. Have Bog look at it and I'm sure he'll give you a pretty good analysis of why it failed.

Unfortunately it is also difficult to inspect such parts for this type of failure. You "might" be able to spot the crack upon disassembly, cleaning and close inspection. I also wouldn't expect a pedal axle to fail so quickly either.

Heal up fast and strong Ken! Sleep lots and rest your brain.

Pretty sure Dave knocked this one out of the park boys. I only did 6 weeks of Metallurgy and that was some years ago….I likely also slept through half of it.

"Fatigue occurs when a material is subjected to repeated loading and unloading. If the loads are above a certain threshold, microscopic cracks will begin to form at the surface. Eventually a crack will reach a critical size, and the structure will suddenly fracture."

"Fracture of an aluminium crank arm. Dark area of striations: slow crack growth. Bright granular area: sudden fracture."

Sept. 15, 2015, 11:41 a.m.
Posts: 2116
Joined: Aug. 4, 2009

It would be interesting to see what hardness that axle is. I bet it wasn't heat treated properly.

Sept. 15, 2015, 12:14 p.m.
Posts: 1647
Joined: Jan. 12, 2010

Add this to my Scarab's seals failing early and the replacement axles squeaking a lot I think I'll pop my Saint pedals back on the big bike.

I'm fat and jump to flat all the time.

Sept. 15, 2015, 12:32 p.m.
Posts: 0
Joined: April 29, 2004

Definitely metal fatigue. Nothing to do with casting, since this isn't a cast part.

sauce: took a semester of metallurgy in colledj, design round metal things sometimes.

Sept. 15, 2015, 12:34 p.m.
Posts: 0
Joined: Oct. 6, 2005

Add this to my Scarab's seals failing early and the replacement axles squeaking a lot I think I'll pop my Saint pedals back on the big bike.

I'm fat and jump to flat all the time.

I am only offering a public service announcement. I can't say anything is going to fail.

I prefer to forget about stuff like that. Biking is expensive enough without replacing perfectly good parts out of unwarranted fear of one off failure.

I have never worried about my pedals failing or handlebars. But, I typically swap my handle bar out on the bikes I ride the most.

A pedal failing has never been something I would worry about, especially with the amount I actually ride in the park. But, I do spend big $ on good gear specifically to avoid replacing my gear too often. I would rather spend on something nice vs spending it twice.

I managed to eat crap in front of my 11yr old demonstrating the trail feature because of a mechanical failure. She found the pedal up the trail from where I was unconscious. I hit the line at my full speed and was planning on coaching her in the drop zones as I had just bought her a new FS bike.

Now I have a kid who may be a little leary of riding. So, next time in the park, I will have to hit the same line again.

Sept. 15, 2015, 12:45 p.m.
Posts: 5635
Joined: Oct. 28, 2008

I bought mine used from Bradical so I'm going to return them to him on warranty. ;)

Just kidding, Brad, that would be fucked.

Wrong. Always.

Sept. 15, 2015, 12:47 p.m.
Posts: 5731
Joined: June 24, 2003

Good reminder for sure. Certain parts on bikes should be retired periodically based on time used rider weight crashes hits etc. I replace helmets every year or two because while I may not have had a single hard blow, there are always a number of low branches and fumbled drops to pavement that will impart some energy. Bars and stems, forks and frames are all things to consider.

Debate? Bikes are made for riding not pushing.

Sept. 15, 2015, 4:19 p.m.
Posts: 5635
Joined: Oct. 28, 2008

Replace our Oldfart
With forum member Newfart
Or risk injury.

Wrong. Always.

Sept. 15, 2015, 4:40 p.m.
Posts: 0
Joined: Dec. 27, 2002

Somehow I cant see this happening on a shimano pedal for some reason. Large companies do proper QC??

I've got decades of riding on my old shimano 646's DX… just sayin. These backyard boutique local brands have their downsides?

Sept. 15, 2015, 5:12 p.m.
Posts: 2113
Joined: May 23, 2006

Critical part failures on our bikes are not acceptable. I would follow up with the Chromag boys on this one.

I'd hire an attorney!

Large companies do proper QC?? These backyard boutique local brands have their downsides?

I just now, like half hour ago screwed some Scarabs onto my cranks and as I was doing so observed the outboard end of pedal wobbling as I threaded said pedal into place.
Picture strapping a pencil to the pedal while doing so, pointed end out, it would have scribed an uneven circle to a piece of paper held up to it.
This tells me the spindle is bent?
I'd expect that from a ten $ pair of peddles, even cheap flats from MEC but I paid over a hun for these suckers. wtf?

“I really have had enough of illogical detraction by association as a way of avoiding logical argument by an absurd extension of ad hominem argument to third parties.”

Sept. 15, 2015, 7:29 p.m.
Posts: 1172
Joined: Feb. 24, 2017

I am only offering a public service announcement. I can't say anything is going to fail.

I have never worried about my pedals failing or handlebars. But, I typically swap my handle bar out on the bikes I ride the most.

A pedal failing has never been something I would worry about, especially with the amount I actually ride in the park. But, I do spend big $ on good gear specifically to avoid replacing my gear too often. I would rather spend on something nice vs spending it twice.

I managed to eat crap in front of my 11yr old demonstrating the trail feature because of a mechanical failure. She found the pedal up the trail from where I was unconscious. I hit the line at my full speed and was planning on coaching her in the drop zones as I had just bought her a new FS bike.

Now I have a kid who may be a little leary of riding. So, next time in the park, I will have to hit the same line again.

oh wow man that's really sad. your poor girl must have been traumatized seeing her dad get injured like that. total sympathy mate that's horrible. i hope you both recover alright and enjoy the sport again. i have no idea what happened of course, i think it was an incredibly remote fluke from a renowned high end brand. i suspect they will find out about this and closely review their manufacturing processes on that pedal.

Sept. 15, 2015, 8:25 p.m.
Posts: 0
Joined: Oct. 6, 2005

oh wow man that's really sad. your poor girl must have been traumatized seeing her dad get injured like that. total sympathy mate that's horrible. i hope you both recover alright and enjoy the sport again. i have no idea what happened of course, i think it was an incredibly remote fluke from a renowned high end brand. i suspect they will find out about this and closely review their manufacturing processes on that pedal.

Thanks.

Sept. 15, 2015, 9:13 p.m.
Posts: 1042
Joined: May 30, 2004

I don't think so. The smooth part is probably a fatigue crack. A closer inspection will probably reveal beaching marks. Once the crack reached what looks like 1/3 of the way through the axle was no longer strong enough and failed. The rough part is brittle fracture. This type of failure happened suddenly across the remaining pedal axle along the grain boundaries (which is why it looks like sugar crystals).

My guess is that there was a small flaw in the axle that created a stress riser. This initiated a crack which propagated across the axle under repeated loading. In other words, a very classic fatigue failure. Have Bog look at it and I'm sure he'll give you a pretty good analysis of why it failed.

Unfortunately it is also difficult to inspect such parts for this type of failure. You "might" be able to spot the crack upon disassembly, cleaning and close inspection. I also wouldn't expect a pedal axle to fail so quickly either.

Heal up fast and strong Ken! Sleep lots and rest your brain.

Exactly what I told Leggatt by text Dave. I haven't seen it in person so it is hard to tell but the beach marks are likely gone from the surfaces rubbing together.

I'm going to put the other axle under the microscope to see how it looks but to be honest I'm not too jazzed about the rough look of the spindle anyways.

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