What Northwind mentions is what I was getting at sillyoldman.

🙂

Sorry, but my exposure to them suggests that they fail at the bosses frequently. I’d love to know the warranty returns rate, but given what I’ve seen, and the experiences listed in this thread, it would be bold to suggest the failure rate isn’t way higher than aluminium cranks.
Carbon is great for making light durable tubes, it’s just that they seem to fall at the “attaching to a spindle or pedal hurdle”. Both pretty critical for cranks.
Variable bonding success combined with the corrosion issue (which you don’t think matters?)is highly likely to be behind those failures, unless you can suggest another failure mechanism?

Back in the day I had one of the first carbon crank sets from FSA. It lasted less than a year with me. Another tale of the alu pedal spline insert insert coming loose.

Most failures (esp Raceface) seem to be early in life. More manufacturing issues than corrosion imo.

sillyoldman – Member

Sorry, but my exposure to them suggests that they fail at the bosses frequently.

Yes they do but that’s not the same as having no chance of lasting which is what you said

Yetiman – Member

robgclarkson – Memeber
5 year old XX1 cranks here, 82kg kitted up and approx 3.5k miles through them and they’re as good as new.

Same here although mine are looking pretty beat up these days.[/quote]

i change the protective tape every year and give the a good clean and regrease every 6 months, seems to preserve them

Everyone I know who’s used Carbon cranks (on an MTB) has broken them – from the 1st set of FSAs I sold to a customer in around 2002/3 to many pairs of RF cranks in recent years – both OEM and AM.
I don’t think my pessimism about their potential life is particularly unfounded.

We can agree to disagree though! 😉

I’ve got 11 year old Carbon Campag cranks which have done a lot of miles on my road bike, and a set of 12 year old ones on my CX bike. They’ve been great – just a set of UltraTorque bearings every couple of years.

I’ve not broken my Next SL cranks yet, had them since Feb ’15 🙂

Next SL, pedal insert, year old, just riding.
I’d had the crank boots on from new and the aluminium inserts looked pretty grey to me when I took the boots off – I suspect corrosion is an issue here – and little rubber swimming pools may not be helping?

Earlier this year I had carbon frame fail, the threaded bottom bracket insert came lose. This was raw alumium, and definitely corroded. I treated the warranty replacement with ACF-50 anti-corrosion spray, but too early to say if made a difference.

Carbon fibre is an fantastic material.

But most commercial airplane manufacturers didn’t dare to use it – for a long, long time…
Reason maybe: the difficulty of quality control and the problem that damages aren’t really ‘visible’.

Bike industry: all the carbon parts made in high quantity in Asia.
And I suspect: no ‘modern’ carbon fibre quality control…?

Ends up in risk for the end user/biker.
We are doing the end of line quality control for carbon parts.
The hard way…

Everyone I know who’s used Carbon cranks (on an MTB) has broken them – from the 1st set of FSAs I sold to a customer in around 2002/3 to many pairs of RF cranks in recent years – both OEM and AM.

I’ve not. I know dozens of people who haven’t broken them.

Had a pair of Next SL for a year without problems. Then, early in a ride, all of the the crank spiders sheared just below the chainring bolts. I wasn’t even trying very hard!
Oh, and I “broke” two Yeti 5c swingarms, but thats got nothing to do with carbon has it!

Time for a Singletrack poll!

Reason maybe: the difficulty of quality control and the problem that damages aren’t really ‘visible’.

and for carbon bike cranks / mountain biking:

small stone stuff is jumping all the time against the cranks.
Other than aluminium: carbon is very sensitive for these kind of surface damages…

bike crank from carbon: challenge to make / challenge to keep intact / challenge for quality control / challenge to check the integrity

Strange how carbon cranks seem a lot more prevalent in MTB compared to road riding where weight/ stiffness counts even more?

Two friends of mine both had new carbon cranks for Strathpuffer, one guys is 9 stone and the pedal thread just started spinning in the crank on week old FSA cranks and the other no more than 11 stone and the same but with Raceface, luckily both had spare bikes.

Strange how carbon cranks seem a lot more prevalent in MTB compared to road riding where weight/ stiffness counts even more?

it’s not about weight and stiffness!!!
👿

it’s a status symbol!
🙄

The critical factor with carbon appears to be consistency, or lack of.

I’ve been running two bikes with X01 cranks for a couple of years without a problem but my mate’s Eagle have failed within months. De-bonded where the carbon’s moulded around the axle/chainring mount.

I’d rather run alloy cranks given the choice but there weren’t many options around at the time that would accommodate a 28t chainring and weren’t black-ano finished, which just looks battered to ….. within days.
That said, I’ve snapped Shimano alloy cranks in the past.

both OEM and AM

Not that that makes any difference, it’s not like they run a 2nd production line with slightly different tolerances for OE kit ahead of AM kit is it.

Had some SixC for about 3-4 months before the pedal inserts unbonded. First ever set of carbon cranks for me, first ever set of failed cranks too. They were warrantied no questions and I upgraded to alu Turbines.

XO came fitted to the Stumpy Evo i had. Not being a fan of carbon i was initially concerned, but several years of riding including lots of jumps, pedal strikes and plenty of crashes changed my mind. They look a little scruffy but still in one (3) piece