Next carbon crank probs

[binner]

can't remember where I read this problem with the NEXT cranks issue of it coming away from axle but mine finally did it so I made a quick fix and it seems to be holding up. Sometimes you gotta think and go hunting.......
Supercheap tridon sump/ radiator parts and boom .. perfect size and crush alu worked a treat.....

 

[The Duckmeister]

Carbon cranks more commonly fail around the pedal thread insert, but around the spindle is basically under the same forces, so not an unexpected failure point. I love carbon, but it is the wrong material for cranks, because in the highest-stress areas it's relying on the strength of the glue between dissimilar materials, not the fibre.

I'd call that a temporary fix at best; for a long-term solution go to an aluminium crank.

 

[link1896]

I’ve a mate who has had the fourth pair fail, all spindle to drive side crank arm.

Hit up Fox Australia for a warranty claim, even outside the official warranty period. They know they have a high failure rate.

 

[Rusty_68]

There's a reason Shimano don't make carbon cranks....

 

[ForkinGreat]

There's a reason Shimano don't make carbon cranks....

Even Shimano alloy road cranks shit themselves , something to do with the bonded parts of the crank arms, I guess. There's a couple of busted axles in there too, NFI if their MTB lines use steel or alloy axles ...

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[Rusty_68]

Even Shimano alloy road cranks shit themselves regularly, something to do with the bonded parts of the crank arms, I guess. There's a couple of busted axles in there too...

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Very true. Everything has a life expectancy. But I can guarantee you, for every Shimano alloy crank that fails, there are three carbon ones that shit themselves. Either way, it's usually due to lack of care by the owner in some way. A lot of these fails stem from the BB being misaligned, the bearings being shot, putting wear and stress on the cranks arms, that eventually let go. I see it all the time in the shop. BTW, I've never run carbon cranks...for good reason.
Stay safe people.

 

[ForkinGreat]

Very true. Everything has a life expectancy. But I can guarantee you, for every Shimano alloy crank that fails, there are three carbon ones that shit themselves. Either way, it's usually due to lack of care by the owner in some way. A lot of these fails stem from the BB being misaligned, the bearings being shot, putting wear and stress on the cranks arms, that eventually let go. I see it all the time in the shop. BTW, I've never run carbon cranks...for good reason.
Stay safe people.

Absolutely. No carbon cranks for me.

 

[beeb]

Even Shimano alloy road cranks shit themselves , something to do with the bonded parts of the crank arms, I guess. There's a couple of busted axles in there too, NFI if their MTB lines use steel or alloy axles ...

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Pretty sure they re-engineered them recently didn't they? Tried to save too many grams and it backfired and they'd buckle and pop open from memory...?

 

[kten]

Next carbon cranks just bring back memories for me of ground-sky on repeat. In one day there was quite a few dynamic failures of carbon cranks of differing brands…anyway, took me down memory lane

 

[ozzybmx]

I've had 2 sets of Next SL's without issue.

First ones were G1's just after they came out, rode them on a fatbike for a couple of years then moved them on to my Evil Following, sold them on that bike.

Recent ones are G5's on my Spur, no issues yet.

 

[The Duckmeister]

There's a reason Shimano don't make carbon cranks....

Shimano did briefly produce a carbon crank to prove they could, but according to their "research" found it no better than aluminium.

 

[The Duckmeister]

Pretty sure they re-engineered them recently didn't they? Tried to save too many grams and it backfired and they'd buckle and pop open from memory...?

Yeah the last generation has a much wider cross-section than previous models, which has helped a lot. That said, although widely reported, failures make up only a very small proportion of the numbers made. The first few generations of hollow cranks were welded rather than glued, and were stronger but heavier.

 

[Rusty_68]

Shimano did briefly produce a carbon crank to prove they could, but according to their "research" found it no better than aluminium.

It was a road crank only though. Highly desirable as a collectors item if you can find one.
Also, if we are talking MTB cranks here, Shimano make a solid product. All those failed Shimano cranks on the insta page are roadie ones.

 

[The Duckmeister]

Correct on both counts.

 

[teK--]

Very true. Everything has a life expectancy. But I can guarantee you, for every Shimano alloy crank that fails, there are three carbon ones that shit themselves. Either way, it's usually due to lack of care by the owner in some way. A lot of these fails stem from the BB being misaligned, the bearings being shot, putting wear and stress on the cranks arms, that eventually let go. I see it all the time in the shop. BTW, I've never run carbon cranks...for good reason.
Stay safe people.

The shimano ones also failed due to glue though!

 

[The Duckmeister]

I've read some hypotheses that the Shimano crank breakages could be influenced by fairly large variatons in ambient temperature. The combination of metal expansion/contraction and changes in pressure in the internal air pocket stress the bond between inner & outer parts.

Given that many of the reports of broken cranks I've seen come from areas with considerably colder winters than we have here, there might be something in it. In all, I've seen only one or two blown-up aluminium cranks, and one split chainring, but many more carbon cranks with debonded thread inserts than I can count.

 

[k3n!f]

Yeah, I ended up fixing my Next SL cranks by buying Shimano ones.

 

[Jpez]

Next carbon cranks just bring back memories for me of ground-sky on repeat. In one day there was quite a few dynamic failures of carbon cranks of differing brands…anyway, took me down memory lane

Oh yeah. Memory lane,
Queenstown TAS, race stage, I come around a corner and and there’s a green Tmac pedal in the middle of the trail, bit weird probably shouldn’t be there , whatevs keep pushing I’m on the clock, then I dunno 15m further on there’s you looking a bit dazed and pissed off with your bike minus a pedal. You must of cartwheeled a long fucking way. Full kudos to you for brushing it off, searching out a replacement (alloy) crankset and continue on with the race! Ah memories. What a day.

 

[Jpez]

Still stuck in memory lane….
Top of the mountain just before @ktens fateful drop in.
in the clouds.

Anyway back on track and as you were. Plastic cranks suck.

 

[beeb]

Still stuck in memory lane….
Top of the mountain just before @ktens fateful drop in.
in the clouds. View attachment 393203View attachment 393201View attachment 393202

Anyway back on track and as you were. Plastic cranks suck.

Now we know why your shorts are feeling a bit tight!