Carbon cranks?

I’ve always had this thing about carbon. I simply don’t trust it on a bike that i’d be riding. However, i’m due my new toy and it has carbon cranks fitted. Not a part i’d associate with carbon, but my thing has steered me away from knowing much about it. I wont have the money to switch them over straight away, and i’m happy to give them a fair chance as they look nice.

Looking at the cranks on my current bikes – they’ve had a hard time. Gouges and scrapes and chunks missing. Can a carbon crank take a bit of abuse? I’m gonna try not to bang them on rocks but there’s no guarantee of that working out. What can I expect to happen if the end of the arm takes a sturdy smack off a rock? Dent? Crack? Shatter? Nothing, just keep on truckin’ 😀

you think they will last lon enough to get you to a place where there will be rocks??

Most bikes are shipped with them as ,lets call them delivery items…a bit like transportation bolts in the back of a washing machine.

I was the same as you but got a little……carbon curious. It started with bars following easton saying their havens were the strongest bars they’d ever made. I loved them. Then came a blur LTc. I won’t go into it, but its a very happy marriage. Now the pushers are showing me ENVE rims………
Seriously, carbon is very very good if done correctly. Alu is also very very good when done correctly.

My old Noirs look terrible now, pretty battered, but still going strong. It’s the metal BB that lets them down 🙁

I decided not to use the X0s that came with my Camber, though. Not that there’s anything wrong with them, but they weigh more or less the same as my haggard XTR M970s, so I stuck with those rather than taking the very pretty X0s and inevitably ruining them.

The cranks in question are SRAM Carbon S-2200s, as fitted to a lot of specialized it seems. I guess they can’t really be that poor.

So less weight (in general) would be the main reason to have them? I’d imagine they’d be fairly rigid but from looking a pics i can’t tell if they’re hollow or solid. Are carbon cranks side-to-side stiff too? I’m a bit bandy and if i’m getting a stomp on, there’s usually a bit of sideways movement around the BB. I don’t want to be riding over my feet 😆 .

I know I should trust carbon and would probably give a seatpost a go, and maybe bars too at some point. Just seems unusual to pop my cherry on a crank.

Personally I would trust a crank to be made in carbon more than any other component on a bike. They are thick composite, which is pretty robust. I would never use carbon bars, and i would never buy a carbon MTB frame. A seat post I would also give a go.

You should be fine mate cranks will need more than a pair of bandy kegs to break em 🙂

sorry………. have i just reopened a post from 1992??????

people STILL going on about carbon and its strengths!!! Practically everything high end or medium end is carbon, pro’s the world over use them in every kind of sport, cars are made from them etc.

Why o why o why do people still think that the slightest bit of wind will break carbon. It SIMPLY just wont. Get over it

edit: i’ve broke 2 titanium bikes, 3 aluminium bikes, 1 steel and 0 carbon. The only thing i’ve broke which were carbon were my Race Face next carbon cranks, which were from 2001 ish and only had carbon inserts in them.

depends on where/how you ride,if you race,etc.
never seen this sort of stuff with alloy cranks,

I’m a bit put off carbon cranks after seeing a set of SRAM X0 DH cranks snap and the sharp end going through a bloke’s calf. A bit sobering to say the least.

I was dubious about using carbon cranks too…the ones I use have plastic caps on the ends though and these seem to pick up most of the scrapes. Apart from rocks flying up and hitting them, I think the pedals and chainring/bash are more likely to contact rocks first.

Just especially for the OP 😉

(downhill version)

And my personal favourite:

Same model as I have on the Soda 🙂 How cool is that?

Yeah carbon does snap but that does depend on what riding you do.

Me, X0 cranks, XC and normal singletrack hacking, been fine.

However I too have seen the female end of the crank arm break out of a set of cranks, but hey..

My carbon frame took a massive bash from a brick sized rock that lept up off the ground and flew into the downtube with a huge thud. Apart from a small scratch in the laquer there was no damage what so ever.

Unfortunately my ankle wasn’t so lucky, and was the rocks next target. When i got home after my ride i could practically wring the blood out of my right sock…….. ;-(

All i would say regarding carbon components is it’s worth looking after them and keeping an early eye out as Carbon has poor abrasion resistance.

Well looks like those laminates are not as thick as I expected. poor usage of inserts also!

radoggair, you clearly know very little about composites. Can I recommend that you send a spontaneous application to Boeing. I hear they need people like you.

Well looks like those laminates are not as thick as I expected. poor usage of inserts also!

I’m glad you just wrote that as when I read your first reply I was thinking “eh?” and had to keep checking it was you that wrote it!

Personally I think cranks are a poor place to choose carbon due to the attachment restrictions for pedals and the susceptibility to getting ‘awkward’ loading (ie someone messing up a jump landing and putting a huge sideways load into the crank)and impact to the crank end or to the pedal attached to it.

Sure if you made the crank out of solid carbon fibre you could probably use it to bash a steel frame into a tangled mess with no ill-effect but to be of any benefit they are supposed to be light. The perfect load case for a crank lends itself very well to composites but in reality I just see it as a bad idea for very marginal gain which just makes me think it’s bling factor.

Although I am sure that someone could come up with a better design than I’ve seen so far and impact worries can be addressed. It’s just a question of will it end up weighing the same as an aluminium crank with any noticeable improvement in stiffness and at something that is not silly price when you consider the normal price inflation of relatively simple bike parts.

The carbon stays on my frame have some deep gouges in from a big tumble a couple years ago and I don’t give them a second thought. However, my alloy SLX cranks are a right mess so I don’t think it’s the best place for the material, road bike yes, mountain bike no.

Cheers for the inspiring images – my confidence is restored 😳

I guess if your’re gonna dip your toe in the world of plastic parts, the cranks a good one to start on. Those pics are telling. The design isn’t quite right.

radoggair – Member
sorry………. have i just reopened a post from 1992??????

people STILL going on about carbon and its strengths!!! Practically everything high end or medium end is carbon, pro’s the world over use them in every kind of sport, cars are made from them etc.

I was doing much more interesting things in ’92. Sorry for coming late to the carbon party 😉

CF is used successfully in many applications, but I can’t see what advantages it has over alloy for a ruffty-tuffty bike crank. A road/race bike, yes. Enduro/dh bikes? Not so sure. Especially if you don’t have the perks of being a sponsored professional.

Euro – Member

Cheers for the inspiring images – my confidence is restored

😆 To be fair, they’re really pretty common cranks, and that’s every pic I could find. The DH ones have had some really bad word of mouth but the standard ones can’t be too terrible or I’d have found pages of them.

Like I say, I’d happily use mine on the Hemlock but it just makes more sense to stick with what I have as it’s already smashed to bits.

A certain WC DH team broke 16 or 17 pairs of carbon DH cranks last year. But it has to be said, for most people, they are more than strong enough.

Snapped mine with chuff all use. Was 10 years ago though!

people STILL going on about carbon and its strengths!!! Practically everything high end or medium end is carbon, pro’s the world over use them in every kind of sport, cars are made from them etc.

Why don’t they make motorcross parts out of carbon then?

Andyl,

Agreed, I guess I was making my first comment based upon how I would have expected cranks to be made rather than how they are made. Those pictures really highlight the dangerous failures that can occur with these materials.

Carbon fibre is of course a great material and can be used with great success and benefit in the right application. However, there is always the danger that people extend its usage to areas where it is not so well suited.

My enduro has the s2200 chainset also and is now 2 years old and been fine.
I’m not mad dh rider but it does get used.
There are a few marks on the ends from ground strike at cwn carn
But they seem fine.

Oddly I have broken my road bike fsa carbon cranks , not a crazy fail like the pics just the pedal insert getting all wonky in the arm.

Why don’t they make motorcross parts out of carbon then?

Like bars?. That was the first link that came up, and folk are saying they look good, but very expensive… Considering they’re about half the price of some of the MTB bars out there I’d say that it’s at least in part because MX guys aren’t as interested in chasing lightweight through things like expensive bars. I imagine more gains can be had by spending money on the thing between your legs that makes it go.

You airbus funded guys….eh

haha carbon cranks brings back memories from the bike shop for me .

fitted some super high end cranks to a fellas orbea orca custom build.

he supplied them.

i fitted them , with the torque wrench on everybolt to spec.

he took it away to his first race and the cranks ended up not in line by the end of the first time trial – the drive side crank had started to rotate on the axle.

got the most irate phone call ive ever had in my life calling me all the **** under the sun because id obviously fitted them wrong…..

as he was ranting i looked on line- here ,” fella did you get these cranks cheap” – “yeah got a great deal , why.” “ive just googled , it seems that most of those cranks fail in the same manor and have infact been recalled so pipe down and i think you owe me an apology”

moral of the story , i have more faith in the carbon component than i do in the bonding between the carbon and the xxx material insert.

you could always buy the alloy ones:

I had some noirs on my singlespeed, they where great. I put a strip of helitape (as i do with most cranks) on the arms for a little extra protection from heel rub. You can also get these, from raceface to protect the bottom.

But really if your not happy with the idea, sell em and get some alloy ones. Tis your bike after all. I always get shot of any part i’m not happy with.

Lots of pics here

Busted Carbon[/url]

I’m sure carbon cranks are fine, if you’re that worried check the warranty.

I’ve managed to destroy 1 pair of Shimano Hones(bent on bad crash), a pair of original saints(rubbed through side with 5 10s after many years), 2 pairs of Truvativ Hussefelts(threaded pedal insert ripped out) a pair of old XTRs.

So you’re going to see horror stories and pictures of pretty much anything you’ll be buying on the internet.

Carbon is amazing if done right. It’s a brilliant material for many products.

Tom KP

If people prefer alu then that’s fine, but to say that carbon has no place on mountain bikes, especially as bars or frames is utter, utter bollocks.
Just because some numpty on STW says it’s not strong enough; it doesn’t make it so. The collective R&D departments of Spesh, Trek, Santa cruz, Yeti etc etc know better.

moral of the story , i have more faith in the carbon component than i do in the bonding between the carbon and the xxx material insert.

Very true, nearly always the bonding that fails.

I’ve just picked up some of those race face crank protectors for my XT cranks. Aluminium/carbon/whatever it can still get damaged from hitting a rock and where I ride has lots of big rocks so strikes do happen.

Oh and rubbing through cranks shouldn’t really be a problem as if you are a crank rubber then just stick a bit of PU tape over the affected bit and it will protect the crank for a long time before it needs replacing. Simple really and stupid not to for the sake of about £1.

I took this picture a couple of weeks ago. Bike is only a couple of months old and the pedal hit a stump on the mellow part of a local DH run.

Saying that, the X0’s on my Stumpjumper are fine even with some wicked rock gouges in them.

If, after all of the above, you’re still tempted by carbon cranks I have a set of RF Next SL’s that I’m looking to shift…

I think prices of second hand carbon cranks may have dropped slightly as a result of this thread.

Top tip with the PU taping. I’ll be doing that, and those end caps look appropriate too. I keep them for a bit and see how they fare. If they break, there’ll be one more pic of a busted crank on the net.

bwaarp – Member

Why don’t they make motorcross parts out of carbon then?

Dunno, might be something to do with the bikes weighing 10 times as much and travelling several times faster, and having many times more power so less concern for shaving grams? Even then, some moto-x parts are carbon.

I’m a bit put off carbon cranks after seeing a set of SRAM X0 DH cranks snap and the sharp end going through a bloke’s calf. A bit sobering to say the least.

I’ve seen alloy cranks snap coming short on relatively small jumps, the going through their calf bit was just unlucky.

I’ve got carbon cranks on the road bike, so can’t comment on their outright strength, but they do feel different, kinda like good carbon posts, they don’t buzz like aluminium.

Watch from 5.00 – this gives me confidence in the robustness of carbon parts on the bikes I ride.

Like bars?. That was the first link that came up, and folk are saying they look good, but very expensive… Considering they’re about half the price of some of the MTB bars out there I’d say that it’s at least in part because MX guys aren’t as interested in chasing lightweight through things like expensive bars. I imagine more gains can be had by spending money on the thing between your legs that makes it go.

Do they make anything that could save considerable weight though, like the chassis? The answer is, a big resounding no.

Dunno, might be something to do with the bikes weighing 10 times as much and travelling several times faster, and having many times more power so less concern for shaving grams? Even then, some moto-x parts are carbon.

Motorcrosses and Superbike riders are all happy to save a 1kg of weight. IMO carbon in mountain bikes was simply brought over from road bikes to appeal to the types who play golf and drive Audi’s. In fact….mountain biking and road cycling is the new golf.

I’ll go carbon when the two wheel motorsport world starts heavily using carbon for stuff like the chassis – instead of one off’s that seem to continually fail (Ducati).

So you’re ignoring the proliferation of carbon in push bikes and deeming it totally inappropriate because motorbikes don’t use it more? 😕

Ok… Personally I don’t think aluminium is up to much because they don’t make shipping containers out of it. If it was all that then surely they’d be alu. I’m going to use nothing but steel, alu is clearly not fit for purpose.