Exploding XX1 cranks.

[Gunder]

While on a ride yesterday my cranks failed with zero warning. See the attached images.

This appears to be a case of galvanic corrosion as the failure occurred suddenly and with zero warning. This is a basic composite 101 design flaw as the cranks where constructed with the carbon fiber in direct contact with the metal insert and zero use of fiber glass to insulate the metal from the carbon.

What is truly troubling is that these cranks have not be recalled due to this inherent design flaw as there have been numerous documented cases of other cranks having the exact same failure method. See the examples that a quick google search finds:

http://fcdn.mtbr.com/attachments/sra...191459552.jpeg

http://fcdn.mtbr.com/attachments/sra...rank-photo.jpg

http://fcdn.mtbr.com/attachments/sra...3-21.19.46.jpg

https://www.flickr.com/photos/88469219@N05/18770636540/

[jetski]

Holy shit! The both failed at th same time? I had those for a year. Guess I'm glad I'm back on metal cranks. You ok??? That could be crash inducing...

[Bruce Springskiin]

That is pretty bad. Hopefully SRAM does good by you for a replacement. If not and you have a BB30 bottom bracket, I have a spare crank set I'll send your way for cheap

[jm2e]

Holy shit! The both failed at th same time? I had those for a year. Guess I'm glad I'm back on metal cranks. You ok??? That could be crash inducing...

Looks like the metal insert pulled out of the crank body on just the one side?
I've got a buddy who's broken his carbon X1 cranks twice. He's very hard on gear though. Sram sent new ones each time.

[kidwoo]

Yup. Those do that. They have ever since they introduced them. They just flat out break in the middle nowhere near an insert too.


Looks like they quit using foam inside of them



If you get a replacement, see if they'll let you have the XO dh ones.

[Gunder]

I'm taking them in to the local dealer that I bought them at this am so they can send them to Sram. Tried contacting Sram via email but have not heard anything back. The only thing with them replacing the cranks, is that I have a hard time trusting them again unless they fixed the design flaw. Pretty obvious it was due to no glass being placed between the metal insert and the carbon. Seems like with an issue that seems this common they would do a recall before someone gets hurt. I was lucky it happened mid pedal stroke in the flats and not during a rougher section of trail.

[HankScorpio]

SRAM requires you to do warranty claims through a dealer but I've found they are pretty lenient when it comes to sending you a new replacement without any hassle. They've sent me a couple Reverbs, shifters and other drivetrain bits.

[jamal]

Woah. I haven't been in a big rush to change my aluminum cranks because they get banged into so much stuff and work with direct mount chainrings.


When I had an issue with my brakes I couldn't even find a way to contact sram myself. They, and other bigger mfgs tend to not want to deal with individual customers anyway. My shop got it handled really quickly though.

[jono]

The only thing with them replacing the cranks, is that I have a hard time trusting them again unless they fixed the design flaw. Pretty obvious it was due to no glass being placed between the metal insert and the carbon. Seems like with an issue that seems this common they would do a recall before someone gets hurt. I was lucky it happened mid pedal stroke in the flats and not during a rougher section of trail.

FYI, glass barriers between carbon and aluminum are not very common these days because galvanic corrosion can generally be stopped with a coating on the metal part. That's how it's always handled on electrical contacts, so the glass thing, despite being widespread in the early days of composites, usually isn't ideal.

That's sort of academic, because obviously you have a failure in the bond between the insert and carbon, but for what it's worth that's more readily described as "materials or workmanship." Not that a design flaw can be ruled out, but it's not the only possibility.

[toast2266]

Those do that. The carbon gets cured with heat, and the carbon and aluminum cool / contract at a different rate, making for a shitty bond.

Solution: if you want carbon cranks, get raceface ones. The aluminum plug in the SixC / Next cranks is all funky shaped to make a solid connection, even with the differential cooling.

[kidwoo]

The biggest design flaw on those is that the walls are too thin. The XO dh cranks aren't really made any differently. Just thicker, a bigger box, and they hold together.

[grinch]

This list of companies I wouldn't trust with carbon parts/bikes is 10x longer than the list with carbon parts/bikes I'd trust. Most of our bikes/parts are manufactured with the simple fact that most of the bikes/parts see 40-60 days of real use on average. A lot of companies parts break or wear prematurely and the companies that may have stuff that wears longer look for anyway possible to escape warrantee or replacement. We're lemmings that easily forget . Best of luck with the replacement. SRAM is atleast good that way fwiw. FTR my xt cranks are 8yrs old and have required zero maintenance. I'm having a hard time trusting anything but. I keep thinking that for the price of adding a few carbon bits I could add a whole other aluminium bike to the quiver. Subject to change of course

[jono]

Those do that. The carbon gets cured with heat, and the carbon and aluminum cool / contract at a different rate, making for a shitty bond.

Solution: if you want carbon cranks, get raceface ones. The aluminum plug in the SixC / Next cranks is all funky shaped to make a solid connection, even with the differential cooling.

There are different ways to skin that cat, too. The composite can be (and often is) designed with the same CTE as the aluminum. That might be harder over small distances (as compared to, say, a structural frame for space applications), but it's also less necessary since the total movement is size-proportional. Not defending SRAM here, it certainly looks like they screwed up somewhere; the complexity of composites mostly just reinforces Grinch's point.

[Gunder]

So Sram is replacing the cranks... but I think I am going to sell them and try something else. After the way these failed I dont think I am going to trust them again without major changes in the construction. Anyone want to buy a new set of xx1 cranks? ha!

[stuckathuntermtn]

Well, don't racing level parts generally give up some durability for weight savings?
That was my impression, but hey, been wrong plenty before.

[Eluder]

So Sram is replacing the cranks... but I think I am going to sell them and try something else. After the way these failed I dont think I am going to trust them again without major changes in the construction. Anyone want to buy a new set of xx1 cranks? ha!

I hear they brake easily so for 140 I'm in.

[zion zig zag]

I hear they brake easily so for 140 I'm in.

I like bikes that brake easy. Breaking easy on the other hand.....

(sorry)

[Eluder]

I like bikes that brake easy. Breaking easy on the other hand.....

(sorry)

Totally called for.

[DasBlunt]

Another reason to stick with Shimano.......

[jm2e]

So Sram is replacing the cranks... but I think I am going to sell them and try something else. After the way these failed I dont think I am going to trust them again without major changes in the construction. Anyone want to buy a new set of xx1 cranks? ha!

Is SRAM replacing the whole crankset? Or just the broken arm?

[Gunder]

Is SRAM replacing the whole crankset? Or just the broken arm?

They are replacing the entire crankset.

[kidwoo]

That's a nasty surprise!
Good think I only have carbon brakes.
As wind chimes.

You eschew the genuinely functional carbon options like frames, rims and yes, cranks. Yet proudly bought the one completely useless functionally absurd and overpriced component of rotors. You makey no sense.

[jm2e]

Nice, that's lucky. My buddy who broke his twice only got the broken arm replaced. So he wasn't able to flip them and move on to something else.

They are replacing the entire crankset.

[El Chupacabra]

the genuinely functional carbon options like frames, rims and yes, cranks.

What's the advantage of carbon cranks?

[kidwoo]

What's the advantage of carbon cranks?

The same with everything else carbon. Weight and stiffness. Find a bike with some race face sixC cranks. Lock up the brakes and just stand on one of the crank arms and bounce up and down. Then hold one in your hand if can. It's insane how little they weigh and they are as stiff or stiffer than some gigantic saint dh cranks.