Ask Pinkbike: Rim Width, Angle Headsets, and Carbon Cranks

 Sorry but thats incorrect. I argue this with my friends as well. If youb put an angleset into your headtube all you are doing is making the steertube sit further back in the top cup and forward in the bottom cup. This essentially 'kicks' the front wheel forward a bit. Now imagine if you kept pushing the front wheel forward what would happen? The head tube would start to lower relative to the ground. Since the frame would pivot around the rear axle this would steepen the seat tube and lower the bb. Draw it out on paper, youll see.

 Yes but the change in seat angle isn't the same as the change in head angle, because the actual height difference change (which is what also affects the BB height/drop) to the front end of the bike, with an angleset headset is a lot less than the change you get in altering the fork length 20mm. You might at best see a fifth of a degree in seat angle change for every degree you alter the head angle.

 The best way to drop bb, steepen seat angle and slacken head angle is offset bushings. Though again, it makes the least difference to seat angle.

 Yeah i had to think about that. I am thinking about a longer travel fork or a 750b wheel to slack the HT angle. Which would increase the BB height and slacken both angles. The head set adapter would give you a steeper Seat tube angle but slacken the HT angle. Good to know.

 So now I have to worry about width and girth plus length. She said it was all about length, now I'm really confused.

 If you want the biggest difference while preserving the current handling, look for a shorter fork and run an angle set. The shorter fork will dip the front end, meaning steeper head and seat angles, then the angle set will sort the head angle out. Roughly 20mm height on a fork means a degree of angle change

 Agreed @deeight, still worth mentioning imo.

 Try offset bushings first, depending on i2i, stroke & travel they can slacken the HT angle from 0.8 to 1.5 degrees, and drop the BB height. Then you can use the 1.0 degree set from Work Components to have the result that you want. You can also use only one offset bushing pairing it with the angleset to test the results and so on ...

 @Deeeight, agree with your statement. also acknowledge that the shorter the chainstay length the larger the affect of an angleset on the seatube, the longer the chainstay, the smaller the affect of steepening the seatube angle

 It really depends, which option is better. I have a WorksComponents 1.5° Angleset in my Remedy, thereby slackening the headangle to 65,5°.
I doubt it affects seat angle noticably. Why? Because the distribution of weight in the uphill also changes. By putting the front tire further ahead, more weight is now lying on the back wheel. This slackening compensates for the described steepening.

BB height is only changed very slightely whereas the BB drastically drops if you try to get the same change in head angle by offset bushings! Also, the ratio curve of the kinematics changes due to different positions of the links - and they will hardly ever change to the better...

 Offset bushes will actually slacken the seat angle and head angle the same amount. Anglesets will result in a steeper seat angle but as mentioned the change is pretty negligible

 Will offset bushings lengthen your chainstays a noticeable amount? It's like riding with your suspension compressed a tiny bit, and unless you have a suspension design that pivots around the bottom bracket it seems like there is always a little bit of movement away from the BB.

 My xc tread conti x-kings in 2.4 are about 2.2 at the tread and 2.3 at the casing on my 28mm light bicycle rims. Very sketchy. Put an ardent up front when the conti started leaking in 2.25- actually 2.25 at the tread, about 2.2 at the casing. It feels much better- at everything. At low pressure the fast rolling contis would lag as all the knobs sagged into the dirt. With the more rounded tread section of the Ardent, it is more predictable at low pressure in corners as well.

 When running 26" x 2.5" Minions, I went from 21mm wide Mavic rims to 25.5mm wide Stans Flow Ex rims. The Stans felt good to very good when riding straight, but as soon as I leaned and pushed them in a corner, they wanted to let go, and to the point where they just weren't stable. The tire would always want to slide out, and not in the good kind of way. This was with a new tire, and I thought maybe it was a bad tire, so I got a 2nd new tire, and got the same feeling. I went back to the 21mm rim, and the tire just felt like it had so much more grip. For the record, I've also used 23mm wide Mavic rims, and those worked great, too. So 21mm was great, 23mm was great, 25.5mm was no bueno.

I rode my buddy's bike with those Stan Flow EX rims with Schwalbe tires (maybe the Magic Marys?), and with that tire the cornering felt very good. I guess it really depends on the rim/tire combo.

 If wide becomes standard, I think tires will have to change. This is a bandwagon you may want to wait to jump on to. I have light, wide rims, that keep tires seated tubeless very well, but very few tires that seem to play well with them.

 Hbfrdh: strange. i've been running 26x2.5" Minions for a long time on Mavic EX 729's (29mm internal), and they've been absolutely great. I then switched to Stans Flow (21.5 Internal) and they lost a lot of stability. I had to run a lot more pressure to keep them from folding in the corners, which in turn reduced the grip dramatically... Now I'm on Flow EX and they are fine again...

 IMO, with current tires:
25mm wide rims are good for 2.3"-2.6" tires
23mm wide for 2.2-2.4" tires, or for maxxis-sized 2.35-2.5".

So I would recommend 23 to 25 mm rims for rockhugger.

Wider rims have pro and cons, but I think they needs specific tires, or wisely chosen tires.

 ^ Not the only person I've seen complain about this.

 All carbon rims will break. Eventually. I've not broken them, but with harsh, pointy rock landings you will crack the rim edge of everything at some point or another.
But the stiffness and the added lightness is unbeatable.
I'm running a set of Nox Composites AM 275 at 35mm outside/29mm inside width with Vigilantes on them. Nice and round.
The grip and control are phenomenal. Sold the V10 and the 26" Enduro and have a garage full of tubeless Minion 2.5s as a result.

 after less than a month? lol

 It's strange how carbon rims are supposed to be indestructible, yet you frequently hear of people cracking them. And I know, nothing is indestructible, but to me they seem like a giant scam. Hugely expensive and still no more durable than regular Al rims...

 It all depends on the rim though. There's ones I'd buy, but everything I've heard about the Ibis & new (M-series) ENVE stuff screams "stay away."

 I can tell you that by experience! now im testing the new Roval Traverse Fattie SL.. lets see how long until they brake !

 fk carbon

 I've had a similar experience with Derbys. If I ran lower pressures, the rim would bottom out on rocks and tear the tires near the bead and edge of the tread. This happened as high as 32 psi, which was never an issue for me on Flows. I also feel like there is a point at which having wider tires negatively impacts cornering. It just makes it harder to lean the bike over. After I destroyed my Derby rear, I switched back to a 25mm internal width rim, and I prefer the cornering characteristics of that width. There may be a sweet spot between 25 and 30, but it's too expensive of an experiment for me to explore further.

 My new bike is going to end up having Flow EXs rather than the wider options I would like purely because of this. Tires aren't keeping up with the new rim widths, we'll have to wait a year or two for tires to catch up.

 Yeah, I think if they could alter the wrap of the tread such that the side knobs were in the proper spot for the current 2.2 equivalent tires, and drop the weight of the Procore type system to 100g per tire, I'll revisit wide rims. I imagine it's going to be a wait.

 The rim damage can be worse with wider rims because the distance between the ground and the rim is reduced and also because there is less rubber on the side of the tire.

 They are the same rim. Ibis says if you want to buy just the rims, get them from Derby.

 They are not the same rim, they don't offer any of the choices I listed above. Ibis should just stop selling their wheels until they sort out the hubs

 The Derby rims are not the same as the Ibis rims. They shared some ideas, processes and facilities, including the same factory, but they are not the same design.

 Copy and paste from Ibis' website:

"In 2013 the first wide carbon fiber rims came out, called Derby Rims. Derby is our good friend and in fact Ibis liked his idea so much we funded half the original tooling expense of these rims. Having access to the Derby Rims proved invaluable in testing for our own concepts and designs. Derby’s rims are made in a different factory than ours, as we will be needing a much larger quantity than his source can provide.

For now, we will only be selling complete wheels, so if you’re looking for rims only, we heartily endorse the product that Derby is selling. If you can get them that is, Derby Rims have been regularly selling out each production run."

 yea but you have to remember its rampage, rampage breaks things that normally don't break

 and they were xo cranks.

 @Cliff-E, yeah, like femurs.

 Which Aggy crash at Rampage are you referring to? The one that wrenched his knee and took him out definitely didn't appear to have anything to do with a crankarm issue, he dumped the bike way before landing. The only other crash that comes to mind was the cased drop and while I could see a crank failing with that impact, they appear to be intact as the bike tumbles down the tranny. Not saying you're not correct, just wondering which crash as the injury inflicting one is the first one to come to mind.

 so far most of my DH friends had broken carbon cranks as well ive seen some custom and prototype and not prototype carbon wheels also at the same state, broken !! So my conclusion is the industry is not ready yet or i haven seen the solid once so far !! Personally I prefer to be aware of carbon seat posts, bars, cranks, wheels because on hard impacts they tend to fail badly !!

 Rampage breaks everything. But i've not heard that this actually happened. If it did, which crank model and a result of what?

 I just don't see the advantage in riding carbon cranks. The weight difference to aluminium (about 60g sram x0 compared to descendant) is not big enough to justify spending at least twice the money and as said in the article they propably don't hold up to gouging as good as solid metal ones.

 If the commercial aerospace industry is ready for composite products, I'm fairly confident the bike industry is too. All that is required is good design and manufacturing methods. Don't tar all composite products with the same brush, there is an incredible amount if variability as a composites strength is largely down to the way it is constructed. And ridethree, perhaps you should look at the crank in question here, you save 195g by swapping Descendant for SixC!

 Airplanes receive a lot more inspection & maintenance than bicycles, especially DJ bikes which are often beaten up hard, put away wet, then beaten up some more. If we had special x-ray machines, utrasounds, and all the other inspection & testing tools (and the experts to use them) found in commercial aviation, and used them on a regular schedule, then yeah, I'd ride carbon everything on my bikes and save a few pounds. But we don't, so I keep my use of composite parts to less critical areas where they don't get dinged up.

 True, though the loading requirements are far more significant in aerospace, I would agree in principle that carbon cranks are not a great idea for a jump bike, just wanted to highlight that carbon products can be trusted for a lot of other applications (including DH) and that there are significant weight savings to be made with a well designed product.

 The Raceface cranks come with rubber boots for the arm ends to prevent pedal end strikes from damaging the carbon, but they only cover an inch or so at the end of the crank arm. A mid-span smack into a curb or rock because you miss-timed trying to get over something will seriously compromise the crank if it scratches into the fibers. Anyone who regularly uses their bash guard to get over logs/ledges and so forth shouldn't be running a carbon crank arm. Even though I primarily ride XC, I am not a fan of dismounting to get past fallen or partially fallen trees or dislodged boulders. I will often try and ride over it and if I get hung up, its usually on the bash guard or the crank arm that is suddenlly experiencing the loading.

 We would agree that carbon cranks may not be the best choice for a pure dirt jump bike build but we would also insist that the Race Face SIXC cranks are designed to take quite a bit of 'abuse'. They are a fully rated DH carbon crankset - not just a repackaged AM or XC crank with a heavier spindle. All 4 Race Face riders that were at Rampage this year - Paul Bas, Mike Montgomery, Bernard Kerr, and Mitch Chubey were ALL running Sixc cranks. They were all hitting huge lines and there were zero issues with the cranks. Bernard and the Pivot Factory DH team raced a full World Cup season on the cranks - while Bas, Montgomery and Chubey were doing slopestyle contests on the same Sixc cranks. Race Face designs and builds its carbon cranks to withstand the normal rigors of riding - of course in crash situations weird loads and forces can be applied to parts that can go beyond what something is designed to withstand. But in reality those same forces that might damage a RF carbon crank would have most likely done damage to any alloy crankset. The Sixc cranks are the lightest DH cranks available that you can trust. In regards to surface damage on the carbon arms - we finish the cranks with a pretty thick clearcoat plus we apply a protective layer of tape across a large portion of the front face of the crank arm to protect against heel rub and trail damage. You would have to scratch the clear coat quite deep to actually reach carbon material. It is best to inspect your bike regularly to detect any serious surface damage to any carbon parts - if you have a scratch or something on your carbon cranks that you are worried about then best to have your local shop take a look and they can refer to RF if further advice is needed.

 I just blew up my old SIXC cranks last week missing tranny on a landing:
www.pinkbike.com/photo/11522266

I'm not sure aluminum wouldve fared any better, but they defnitely can explode

 I already saw two sets of SIxC cranks fail around the pedal mount and never heard anything happening to X0 cranks. Mine took a really hard hit two weeks ago and nothing happened, just the massive clearcoat layer got a bit less massive. On the second hand market Sram carbon cranks have some great prices, negating the sense of buying anything else above SLX or Zee. I paid the less for pretty much brand new X0 than for my wives second hand RF Turbines.

 I've seen the same happen to XO dh cranks, didn't happen in a crash either. Just because it's manufactured in a different facility doesn't mean it can defy the nature of the material.

 At bromont i saw a guy with his xo cranks snapped. And have heard tons of stories of that happening. Never heard a bad word about sixc til now. But everything breaks at a certain point as well.

 Nothing is bomb-proof, bomb-resistent is the best you can hope for.

 What about nukeproof?

 @Waki - in Photos (broken parts category) 2prs. of broken XO's in March and another 2prs. in May.

 lol I've seen plenty pics of broken carbon sram cranks

 For anyone concerned, the failure that regdunlop38 has experienced is on the older style SixC cranks (as he rightly says). The new SixC cranks pictured in this article have been reinforced in that area to prevent the issue.

 @WAKIdesigns - clearly trolling lol

 @dugglesthemuddled - The commercial aerospace industry has the capital (and the need) to enforce very tight manufacturing tolerances, scheduled inspections, and very close tracking of the service of their parts to a much much higher standard than would ever be practical (or even possible) for a personal bike application. I agree composites are here to stay, but I think it's naive to base support your argument by comparing these two very different industries.

 @racefacesuit that's a bunch of BUuulllllll$hit. My Sixc cracked well above the pedal insert when I clipped a rock and no warranty as given. It was the only time the crank as ever tested and it failed.

 @Laynehip - please get your facts straight.

Aggy bailed over the Polaris hip jump throwing his bike from an extreme height. The bike landed on the drive side directly on the pedal and bars. This damaged the crank, derailleur hanger, bars, brake lever, and other parts.

An impact like that from the side of the bike is not what those parts were designed to sustain. The damaged parts DID NOT CAUSE Aggy's bail, they were a product of his bailing and tossing the bike.

I agree that carbon cranks on a dirtjumper are silly. I believe that all else regarding carbon cranks is opinion here. I just wanted to clear up your initial statement which was not true.

 @Neverlost Sram Sympathizer!!!

 www.pinkbike.com/photo/11509461

 I see a grenade chasing him mid air

 fk carbon

 Nothing better than a cold beer and cigarrette to forget about broken crank but dont litter bro!!!

 @redunlop38 Nothing better than a cold beer and cigarrette to forget about broken crank but dont litter bro!!!

 @laynehip - not so much. I base my observations strictly on the fact that I was there. Keep in mind here that he bailed. He did not land with the bike.

Your picture shows it perfectly, the crank broke on impact. He did not land on/with the bike, so is your assumption that the crank magically broke mid air or before the jump and stayed perfectly with the bike until the impact? nope.

Go huge like aggy, toss your bike, if it lands directly on the pedal and generates massive side loads, your crank may break. That is all there is to it.

 Never lost is right though, anything and break and rampage is the testing ground for limits of parts and bodies. I've been three years in a row and anything and everything breaks.

 "But in reality those same forces that might damage a RF carbon crank would have most likely done damage to any alloy crankset" props for RF taking part in discussion. however unless they or somebody presents scientific data that carbon =alloy it is all PR bs. oh i know: ENVE should also take part in the discussion if they got balls.

 @ekho - the reality of "science" in cycling industry is that they take an existing technology, apply it to a bicycle specific product and test it in the ways of Myth busters. There is nothing wrong with that because maybe, there is nothing more to do. What is disturbing though is the people who believe there is some "real science" going on, and demand "scientific data". If one demands it, then he must be able to evaluate it, value the methods used to "experiments" - otherwise forget it, it will be just meaningless goo that one can use only to pretend to other people that he understand what is going on. If the data is supposed to be "scientific" then it has to be put into a document that has to be approved by an university, furthermore put into an article into scientific journal. I'd like to see those papers in science journals about wheel size hahahah

There is a reason why there is no "scientific data" shown by almost any company - because none of any quality is ever produced. There are very few companies dedicated to testing like for example Syntace. The industry has a remedy for it: it is called low cost, high margin production, paying itself off in ability to pay insurance, warranty and eventual recalls. Finally lack of "scientific data" is good for marketing, they can propell as many half-truths and pseudo-science as they want. A science that truly works in cycling industry is psychology of purchase.

Disclaimer: that was nothing negative against you, I am with you, just clarifying PB engineering.

 To be fair, Syntace had to develop some serious testing methods because their original products were fragile crap, especially their handlebars. Around 1994 during one of the two Reebok Eliminator events (head to head racing down the Mammoth Mountain Kamikaze DH course), Jimi Killen hit a pothole and his lightweight specialized aluminium bar SNAPPED just outboard of the brake lever clamp (frame captures of the video - there was a helicopter right above them filming it - showed the bar section with grip and bar end bouncing along during the crash that followed). A few months later Bicycling magazine got a university to build a bar-tester for them, tested a bunch of bars, and then published the results along with an explanation of the test equipment. The second worst bar tested was a Syntace, which failed at an impact force of 175 pounds in a drop test, and 2,103 cycles of the fatigue test, for a then $65 / 131 gram flat bar. In comparison, the Answer Hyperlite bar, long considered the benchmark standard for lightweight bars, was $5 cheaper and 13 grams heavier, but lasted to 595 pounds in the impact test and 19,460 cycles in the fatigue test. A $50 (and virtually identical weight to the Answer) Specialized team bar like Jimi broke failed at 280 pounds in the impact test and 11,767 cycles.

 @WAKIdesigns - agreed!

 With all due respect deeeight, that was 20 years ago... BTW Where on earth do you get those numbers from?

 Bicycling Magazine, like I said. They PUBLISHED the testing results.

 I was rather terrified that a human being QUOTES such stuff and I pray he does not REMEMBER it.

 I remember highlights from it, the klein stratum bars were 99 grams and basically outlasted the fatigue test (the operator grew bored when the third bar was doing the same as the first two, just running the counter into six figures and switched the machine off), and that the hyperlite was the best for impact testing. I also remember that even the cheap $25 Zoom 170 bar, something that was heavily spec'ed OEM on a lot of mid-level brands at the time, did far better than the Syntace and even better than some of the bigger name brands.

 Yes, but times have changed over 20 years and Syntace is at the forefront of "publicly available" testing. I have their 109 stem, 97g at 60mm. When I opened the box with it, I went, sht that is narrow, it is the Megaforce that I should have bought. Despite scepticism, and getting mentaly biased I do not FEEL any stiffness decrease to replaced 50mm Thomson elite which is damn bulky and 70g heavier, and I have uber stiff Renthal bars on it. I'd have to compare it to a monster like 50mm Holzfeller to feel the difference.

 Yes, but you're as typical for you, failing to grasp anyone else's point. In this case, Syntace HAD to step up in terms of publically available testing, because their previous in-house testing was non-existent, and when their stuff did get tested, it was by magazines which were revealing that their lightness came at the expense of durability, in a major way. In general its accepted that designs have to balance costs, strength and weight... but when you fail to consider any reasonable amount of strength at all simply to hit a target weight... well that's a serious problem then. As it is, they're still lacking in durability in some areas (RC's reporting that you have to re-check the tension/true within 200kms of riding on their wheelsets... i'm sorry but for the money involved, the wheels should be flawless from the start otherwise you might as well just handbuild your own... Shimano wheels aren't going to go out of whack in only 200kms and neither would Mavic's).

 And you are basing that on an article from 20 years back, interesting. As to their wheels, only a fool would buy them considering that their rims are avaliable to buy as spare. Mavic has enough sins in hubs department, Shimano... go to the closest workshop and ask about axles and freehub bodies in their 142x12 hubs... some companies like Easton haven't learned anything through many years, they simply rely on warranty. For MOST mass produced brands, warranty returns and recalls are worth it. If it wasn't so, even for smaller companies, Evil would not exist anymore. There are areas of science called "risk assessment". Testing is next to worthless when faced with another "modern" branch of science: quality control. Some people are unfortunate to grasp the fact that Physics of MTB design have to fight with psychology, public relations, risk assessment, quality control and the simple bad luck or data manipulation.

Science has replaced Church - people eagerly seek a man who will tell them a complicated story on how the world works and their lack of knowledge in a specific area forces them to use faith, a belief that what he says is true.

 Ahhh and I usualy fail to grasp particularly your point of view, as you base most of your opinions on stuff that happened looong time ago, like the time you judged 26" wheels by riding your FS bike from 90s. I rode several 650B bikes, including total porn, like carbon SC 5010 and high end Jekyll, and I think of you everytime I sit on one - what a load of bollocks, waste of time and resources they are. Poor Kirk, he made an excellent thing, wide rims at staggering low weight, that actually hold up to abuse, why blur it with that diameter crap, why, just to lower the BB, because a bunch of morons aka buying force did not want to learn pedal stroke timing. If only he focused his efforts on width/weight ratio we'd have those things popular ages ago. Instead we got bullied by Mavic you praise and their idiotic 17 and 19mm XC rims

 Yes because you know more than everyone else... Giant included who for 2015 have NOTHING but 650B mountain bikes.

 Pretty Sure Santa Cruz did quite a few tests for people to see instead of making some stupid ass journal and submitting to Universities wasting everyones time on sport nobody cares about but us. You forget we get to watch World cup races live, Rampage live, and its not very often you see catastrophic failures. So until people are really in harms way and losing limbs or dying its really not that big of a deal if the products last and they have warranties etc. So........ shut up with your bicycle conspiracy theories.

 @airmiller44 stupid ass journals! stupid science! Shut up, shut up!!! I BELIEVE in carbon, i do not question carbon, praise the CARBON!

 Seeing is believing. Some nerd writing a paper isn't. Proof is in the pudding. My point is don't create a problem where there isn't really one. All these crazy conspiracies are Bullshit they are fucking bicycles not Ebola

 I think you're right. In my neck of the woods riders seem more concerned with their bike than their abilities. Very few folks really NEED carbon anything.

 I thought the same thing until I rode carbon rims for the first time, making no other changes to my bike (and using the same tires). There is a major improvement in stability though chunder due to the added stiffness. It makes more of a difference than a through-axle. Aluminum rims (Stan Flows, my prior rims, which I also like) are simply not in the same league. And it isn't the weight savings that matters so much, it is WHERE the weight is saved -- at the outside of the largest rotating masses on the bike. There is a significant increase in snappiness of acceleration when climbing. Do you really need it? No, of course not, unless you are racing XC. But dang they feel good to ride. (Now using Roval Control Carbon on my HT and Derby Wide on TBLTc)

 "looked like it was stolen from a YZ450"
take my money Ibis

 I believe the plural form of Ibis is Ibi

 I believe it is ibis.

 Agreed. I have a Slayer (HA=66.5) and installed a CaneCreek -1.5 headset to make it 65deg. I don't find the bike to have any less less pop, but the steering is quite sluggish. I also have a -0.5 cup to try out, but I think I will end up opting for a -1.0 cup in the end... We'll see. The main take away is that if you modify your head angle by 2deg, it's going to be a waaaaay different beast. I'd make a slightly less drastic change if I were you.

 @joemo5 What fork are you running? I've got the same bike, and i've been thinking about installing a -1.0 works headset, but I already have a 180mm Fox Talas so I'm not sure wether it would be too slack or not...

 Also, I wouldn't worry about the change affecting your Seat tube angle and BB height. The difference in the height of your front end won't change by much when raking out your fork by a couple degrees. Also, when you add a thick lower head set cup to a head tube that is designed to be internal, you are just raising that height back up by around 8mm or so. Food for thought...

 I have a 2012 Slayer and it came with a 160mm (fox 36) fork, I popped a 170mm fork (x fusion vengeance) on it, should I do anything with an angleset or will it be fine?

 finnrambo, that fork will raise up your front end a bit compared to the 160mm fork. The difference in HA is probably less than 1/2 a degree to the slack side so you won't change it that much. I guess the question is whether you want a slacker bike. If you do, and you added and angle set, it would add some height to your front end. That would be on top of your increase in height from your fork. So keep in mind, if you want a slacker bike, it costs you a bit of stack below your head tube.

 Thanks! I'm not too worried about the height below the headtube so I'll just leave it as is with the 170mm fork and grab an angleset if I still want a slacker bike after that.

 A little late here but works connection makes anglesets that have zero stack lower cups. The reign I have retains nearly the stock geo except for the HA with the ( @elias15 ) 160mm fox 36.

www.workscomponents.co.uk/15-degree-ec44---zs56---to-suit-tapered-steerer-tube-forks-138-p.asp

The ZS stands for "zero stack" while EC stands for "external cup" or something similar. The numbers are the ID of the frame (OD of headset cups)

 I've seen aluminum cranks snapped near the pedal too.

It is an interesting question... just how tough are carbon cranks. So far I've only heard (and provided) anecdotes. My observation is that there is nothing to suggest that carbon is more likely to break.

 I think the real question is, what are the benefits to carbon cranks v. AL? (Besides bling...) Are they that much lighter/ stiffer?...or is it just a trend that makes $$$

 I think the Cost to Weight Savings ratio isn't good enough for most DJ riders to really take the risk on carbon cranks, but that's just me. I beat the cr@p out of mine, so cheap and strong is the way to go.

 josh090 - they are much lighter and stiffer for the weight. But yeah, that difference isn't worth the cost to a lot of people.

I've bent an aluminum crank (spider) beyond being able to use it. I've yet to do that to carbon. Not that this proves anything.

 Cheap and strong. That's why most street/dj riders run bmx cranks.

I've got Powerbites on now, and they're solid as Fu¢k.(literally and figuratively)

 dfiler, that's another issue I suppose, with your alum. cranks you bent them...and then switched them. Carbon doesn't bend, its strong until it fails. (so there is really no warning signs).

But yah I agree, the difference isn't worth the cost

 Too bad they don't still make diablous cranks, still running em on my DJ. strongest alu cranks you could buy, but still a bit lighter than steel. Plus they look manly.

 You shouldn't forget that a scratch in carbon components isn't at all the same thing as a scratch in aluminium
Scratched aluminium is just "meh, whatever", but if you scratch carbon you're going to compromise the structure and arrangement of the carbon fibres, thus weakening the component (because without a proper structure and arrangement of the fibres, carbon is pretty much just regular plastic)

 Tell you what mate you must have bloody thick finger nails. I was thoroughly inspecting a Renthal carbon bar last week and they were easily as thick as an Ali bar.

 fabdemaere - the strength of carbon fiber is from the carbon fiber, not the plastic bonding it together. when there is a structural failure, it is because the carbon broke. The plastic is fairly meaningless in that context. Scratched carbon only weakens to the depth of the scratch. That is the point of the whole thick vs thin carbon discussion.

Matt76 - I was referring to the ultra light weight carbon bars weighing in at 180g to 200g. The renthal you mention is indeed thicker and is also almost 50% heavier. Again, distinguishing between thick and thin materials is critical. Ultra thin walled components can be ruined by minor surface damage. The same is not true of thick walled components.

 Interesting that this is being downvoted. The bulk of pinkbike readers must not be ready to look at the difference between thin and thick walled carbon. My bet is that someday they will begin to make that distinction. It really is a significant difference.

 dfiler i'll presume this was downvoted from this kind of a mass already tricked by the marketing tricks to sell you new carbon technology for applications that require not only stiffens as well they must be safe and secure once this type of mass has an a terrible accident because carbon failure they will be on my page. Carbon tends to fail couse the micro-fractures thing develops over the time no matter thick or thin layer of carbon has been used for those applications also carbon is vulnerable to a temperature differences that moment when you leave your bike outside on the balcony and outside is sunny like hell and your dear carbon frame is pained black and you get out for a ride and abuse the product could lead to fail too...
i will presume this will be downvoted too and i wish to the downvoters to buy a new carbon spring as soon as it gets on the market

 Micro-fractures are also theoretically a problem with aluminum as compared to steel. And yet we see tons of aluminum on DH bikes.

When you say "carbon tends to fail", i presume that to mean in theory. There's no evidence that modern free-ride or DH specific carbon components and frames have a higher failure rate than aluminum.

 This is maybe road bike specific but it makes for worrying reading non the less

www.irishtimes.com/sport/other-sports/carbon-fibre-bicycles-in-the-frame-for-rising-number-of-injuries-1.1879653

 well carbon dates long time ago i personally have a best friend in carbon industry who is also a developer. His main business is a car elements not involving a torsion and still be capable to sustain high impacts in case of a crash. So i was told no to invest even a penny in carbon elements couse the industry is not ready yet and there is a lot of unbaked up advertisement corrupted results and ect just to drive the industry to make cash. Even if he is not right as a proof i can tell you all my friends ware rushing to get carbon cranks and all of them ware DH broken related with some serious injuries, personally i ve broke seat stay and a bar consider my other aluminium boobar lasted 4 seasons and its still going on after a terrible crash when the carbon failed on riding on my normal DH position leaning a bit forward before the burm so im confident for now i ll stay away for a while of carbon stuff

 I've done 100's of warranty inspections for customers the past couple of years - for both carbon fibre and aluminium alloy components including frames, bars and cranks

Most of the carbon fibre I have seen with 'catastrophic failure' has been involved in an impact way beyond a reasonable engineering scenario like riding square into a tree at 30mph, driving into a garage with bike on roof of automobile, or the cyclist being run over by an automobile on the highway.

The carbon fibre I have seen with some mode of failure but not catastrophic (i.e. slowly propagating crack in frame) has been determined to be from issues with design/engineering (you see the same issue on repeated units of the same model), quality control during manufacturing (bad layup, issues with handling damage to cloth) or historical legacy (metallic elements moulded into carbon fibre i.e. BB shell causing galvanic corrosion over several seasons)

I've seen a lot of broken CF and Aluminum alloy parts. I happily run a road bike and mountain bike both with CF frames, CF seatposts, CF bars.

I would not use CF crankset because there seems to be no real advantage, and a huge cost penalty. Several years back, Shimano (easily the leading producer of cranksets) brought a CF "Dura Ace" road crankset to market. Then withdrew the crankset as there was no advantage over their duraluminium model, a big cost penalty and rumours had surfaced of failures with the CF crank.

 I've seen a good number of broken SRAM XO CF cranksets, usually the pedal boss ripped out or the end of the crank arm fractured from rock impact.



Also seen a good number of bent aluminium alloy cranksets from Shimano, RF, SRAM / truvativ and other smaller brands, but very few that have failed completely - I've seen more broken cromoly steel cranks from Profile when I rode BMX for many years - seeing something skating across the floor of the skatepark and its a Profile race crank arm with pedal, the arm has sheared off at the axle boss where the weld has failed.

Bending is a good safe mode of failure for the rider, a sudden failure can easily cause a broken ankle, broken leg or other serious injury if the rider is thrown off the bicycle at high speed.



The CF cranks seem to be the ones with the catastophic failure, probably from previous impact damage compromising the CF structure.

Alloy cranks seem to take a regular beating with little consequence. Of course, its wise to always inspect your equipment before riding. The tricky thing with CF is you cannot really determine what the previous impact did to the structure, unless you have access to NDT equipment which is beyond the cost and availability to most riders, let alone companies.

 www.pinkbike.com/news/Syntace-W35-MX-Wheels-Tested.html

 I'm running two bikes with Syntace MX 35 wheels. They are super lightweight and will get out of true if you don't check for tension a trueness after the first 200 kms. After that, mine have remained straight and tight. Some tires are hard to mount up tubeless, but most air up easily with a Gorilla tape setup. The rim will ding if you are running low pressure and smack rocks, but If you prefer aluminum and want both wide and lightweight, they are a good choice. RC

 thanks, rc!

 Hmmm, I was under the impression they were quite sturdy: www.youtube.com/watch?v=GuUkASfGOwo

The W35MX rims are a top of my list. The hubs are pretty cool too.

 1) A large effect, you'd have to try them yourself to see if you like the feel.
2) I don't have experience with Anglesets so I can't help you with that.
3) I wouldn't worry about flex with carbon, carbon when done correctly makes for an incredibly stiff product.

 I am also curious about this. Wouldn't an angleset create extra leverage and stress on the head tube? For example slackening the head angle by 2 degrees is equivalent to the effect of a 40mm increase in the A2C height without the actual height increase.

So if we don't suggest such a change would it be wise to use an angleset that will create the same effect?

 It may be the same effect as 40mm a-c height but the important part is that it isn't, is it? All you do is alter the angle the forks leave the frame so by my thought there is zero increase in leverage as the lever isn't longer.

Anyways, this is 2014, manufacturers like commencal, scott, intense etc etc all spec bikes with anglesets etc - its a total non issue.

Carbon cranks seem hit and miss, seen some break and some last 2 seasons...

 I am OK if something is within the manufacturer standards or even suggested by the manufacturer but the 2.0 degrees angleset seems quite a lot to me. Also speaking about the potential extra stress on the head tube maybe the leverage isn't really the cause but the slackened HA could for sure cause some issues. To explain this with an example just put a stick vertical to the ground and try to push it. Nothing will happen. But as you change the angle it would be much easier to flex it.

 Stop overthinking it and slacken that steep reign off of yours!

 For now 66 is quite OK (it is the SX with 170mm Lyrik RC2DH) but maybe I will give it a try in the future.

 Hi there.

As racer951 said above there is no real increase in leverage and as the angle change is quite small in real terms ( less than 5% of original) additional frame stress is minimal.

We have made 3.0 degree headets in the past for wc dh teams and in many years of trading have not received one report where a user has believed frame failure was brought about as a result of our headset being fitted. Thanks, Rick@works

 ΟΚ. That's great. What angleset would you suggest for a tappered fork and a 44-56 head tube?

 We supply an Ec44 / Zs56 headset to fit - external upper and internal lower. This is available in 1 & 1.5 degree options with a tapered fork. If you need any further info please contact us through sales@workscomponents.co.uk or www.workscomponents.co.uk - Thanks!