Ask Pinkbike: Carbonphobia, Choosing a Rain Shell, and Hydro-Pack Alternatives
Here at Pinkbike we get inundated with all kinds of questions, ranging from the basic "Can I have stickers" to more in-depth, soul searching types of queries like if you should pop the question or what to name your first child. Ask Pinkbike is an occasional column where we'll be hand picking and answering questions that have been keeping readers up at night, although we'll likely steer clear of those last two and keep it more tech oriented.
Carbon Questions
Question: Pinkbike user reynamwit asked this question in the Bikes, Parts, and Gear forum: I recently bought a used Demo 8 I and would like to replace the stock handlebar with something wider. I did some research and was thinking of picking up Deity's DC31-Mohawk, but some people that I've talked to seem scared of carbon handlebars in general. What interests me in going with carbon is the shock absorbing properties that some are said to provide, and the whole being scared of carbon doesn't make sense to me given that it's supposed to be stronger, lighter, and more resistant to structural fatigue than aluminum.
 | There are people out there who will never run a carbon fiber anything out of fear. That sort of thinking is unsound, for the most part, and is usually the result of them having seen a failed carbon component that didn't seem justified. There being a ton of photos online of broken carbon stuff, most of it with the owner either not realizing why it failed or not explaining it at all, doesn't really help the case for carbon. I've seen a lot more broken aluminum bars than carbon bars in the last twenty years (although aluminum surely outnumbers carbon 100 to 1 over that time) and I'd personally trust a carbon bar so long as it was looked after. And that's where there really is a difference... nearly anyone with a hex tool can install an aluminum bar and not mess it up, you can scratch the hell out of it without worrying as much, and you don't have to be concerned about things like tie-down hooks on it. Bottom line: an aluminum bar is better for a rider who is ham fisted, rough on their stuff, or doesn't inspect their gear every now and then. Carbon components can be made to be stronger, no doubt about it in my mind, but they can also more susceptible to damage. As for carbon's damping abilities, I wouldn't be too concerned given that you have eight inches of travel, a massive tire with about 25 PSI in it, and are a recreational downhiller. To be honest, most of the new carbon handlebars out there, and especially those that feature a 35mm stem clamp section, are very stiff and unforgiving. My advice would be to find a handlebar with the geometry that you prefer and then go from there, and spend the extra coin on a carbon bar if you look after your stuff and wouldn't mind the weigh savings. - Mike Levy |
Deity's DC31-Mohawk looks like a great carbon handlebar, but that doesn't mean that carbon bars are great for everyone.
Good quality waterproof jacket for under $125?
Question: Sewer-rat asks in the All-Mountain and Cross-Country Forum: I'm looking for an okay waterproof breathable jacket for around $125 max. I know the difference between soft / hard shells, but was wandering what people are using and how they work in regards to heat etc...?
| During my time living in the Pacific Northwest I've tried all manner of waterproof / breathable jackets, with prices ranging from inexpensive to astronomical, and in your price range the Marmot PreCip ($99) is one of my favorites. It's not designed specifically for cycling, but the hood will still fit over a helmet, and the arms have enough length and articulation to keep them from riding up or hindering your movement on the bike. It also has long pit zips, which are a necessity for those warm and wet days where maximum air circulation is required to avoid feeling like you're wearing a plastic bag, a common occurrence no matter how breathable a jacket claims to be. In addition to all that, the PreCip will pack down into its own pocket, making it easy to toss into your bag just in case those threatening dark clouds decide to start pouring down rain. - Mike Kazimer |
The Marmot PreCip jacket does the trick when the weather turns nasty.
Hydration Pack Alternatives
Question: Farry asks in the All-Mountain and Cross-Country Forum: Yo, I'm not overly fond of riding with a bag on and was wondering if anyone had any great solutions for getting the kit required for racing (tools, water, first aid kit snacks etc.) on to the bike or person in other ways? I currently use a Dakine drafter bag, not a bad bag, but it moves a bit when riding. Maybe there are some better bags out there that would be worth considering.
| Enduro racers must be self-sufficient during their race runs and some tape their essentials, like a mini-tool, some tire levers, a CO2 kit, and a spare tube under the top tube, and use a frame-mount water bottle. Tuck food into your pocket and you should be ready to go for a bit more than an hour of racing. Specialized makes the SWAT (I think that stands for, "Spandex With A Twist") bib shorts, which are a PB favorite. SWAT shorts have slim pockets sewn into the back, designed to be secure storage for water air and tools. You won't be jeopardized by having 60-percent of your body covered by skin-hugging Spandex in public, because the comfy bibs are intended to be worn under baggy shorts and a loose-fitting jersey. - RC |
Anneke Beerten simply tapes her essential tools and spares to the top tube of her frame - a simple solution perhaps, but nothing rattles and it keeps everything organized in plain view for a quick track-side repair. Specialized's SWAT bib shorts are much less cumbersome than a hydration pack and store similar items in a more convenient manner.
Have some unresolved tech questions? Jump in the Pinkbike Forum and we'll look to answer it for next time.
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These are other carbon fiber facts:
sustainability.stackexchange.com/questions/1125/can-carbon-fibre-be-recycled
www.answers.com/Q/How_do_you_make_Polyacrylonitrile
www.zoltek.com/carbonfiber/how-is-it-made
I have a lot of time!!! Wooo long winter breaks!!!!
The aluminum bar probably has a higher carbon footprint than the CF bar.
Sure, there's less carbon in the end product, but mining and processing aluminum is a nasty business. Consider the impact of deforestation from mining, the massive amounts of petroleum products that are burned just digging aluminum out of the ground and transporting it, and the actual processing that goes into aluminum.
Also, when I'm done with my carbon bars, I just burn them into a cloud of dark black smoke. I inhale as much as I can as to prevent the smoke from depleting our carbon monoxide supply, sending us back into another ice age.
#science
To the guy above, I've recycled many aluminum bike parts. :shrug:
As long as carbon fibre structures like bicycle frames and handlebars are used within their design / engineering specifications; they will outlast aluminium alloy structures by many years, as aluminium alloy fatigues with each loading cycle.
Pretty much all of the carbon fibre structures I have presented to a manufacture for warranty (I am talking 100s) have been from:
1. Road traffic collision or riding into a tree on a trail / binning bike into rocks (sudden, and massive overload beyond design specification). Nothing can survive this instance. Normally dealt with under "crash replacement" schemes.
2. Galvanic corrosion (metallic elements embedded in a carbon fibre structure). This is eventually designed out by a revision of the product.
3.Miss-handling by the end user, such as over tightening a handlebar stem and cracking a carbon fibre handlebar, customer admitting they did not own / use a torque wrench.
4. Historical design flaw on a specific product - you see the same claim on a number of the same products. This is eventually designed out by a revision of the product.
My my bikes are carbon fibre, and both my handlebars are carbon fibre, no concerns here. Have seen a lot of broken cromoly steel, aluminium alloy and carbon fibre, even some titanium alloys, over the years.
Seriously, there's no such thing as a carbon part made from 100% carbon. There's no industrial option to recycle any epoxy composite (like "carbon" the way we use it) 100%.
Still, if you really wanna work on your footprint: RIDE YOUR BIKE TO WORK, promote cycling in your neighbourhood/city, or at least, consider car-pooling when going to the bike park.
You took them to the facility, asked if it was OK to recycle, or just put them in the blue bin for the truck to "take away"?
@MatthewCarpenter the linked posted about (sustainability.stackexchange.com/questions/1125/can-carbon-fibre-be-recycled) specifically addresses the epoxy.
Carbon fiber also fatigues that's not just for aluminium...
Yes, maybe carbon is recyclable but the most important thing that people forget is: is there a carbon recycling plant near you? The answer is very likely to be no, as opposed to shops buying metal which are all over the place.
Don't forget the 3 R's:
-Reduce
-Reuse
-Recycle
It's hard to apply to the bike world but recycling is not an environmental savior, it should be a last resort.
1 Reduce..Buy parts only when you need them. Buy quality parts that will last a long time.
2 Re-use. Buy used parts. You can do that right here. Use parts from your old ride if they are in good shape.
3 Finally, Recycle. This is still a good thing but is the last on the list,
The democratic world works in large part due to public policy, which is when the public sees a problem and the policy makers respond to the problem. Buying hybrid cars is a market signal for policy makers that will trickle up to the producers as a result of slow change over time.
In other words, buying a hybrid car does change the world. Its sort of obvious that one car is not going to change the world on its own, so I don't really understand the point that you are trying to make.
... unless you are saying that we should abandon consumerism/liberalism in favor of living in a stone age where fire isn't a thing, we should only travel by foot, produce our own food, and be completely independent of the advantages that technology give us to make the world a livable place. If that's what you are arguing for, you might have the wrong idea about environmentalism.
And old read, but still relevant:
www.compositesworld.com/articles/carbon-fiber-life-beyond-the-landfill
Aluminium alloys, unlike steel alloys, do not have a fatigue limit. If a cyclic load is applied, aluminium alloys will always fatigue.
Mild steel will not normally admit fatigue crack growth if the applied stresses are below about 10% of the strength of the material
This is why so much effort is expended on NDT and rigorous inspection of aircraft assemblies made from aluminium alloys, even when designed within their specification limits. Over time, they fatigue, and can eventually crack leading to failure.
. "A material data sheet [5] defines the fatigue limit under cyclic load as 14,000 psi (100 MPa) for 500,000,000 completely reversed cycles using a standard RR Moore test machine and specimen. Note that aluminum does not exhibit a well defined "knee" on its S-n graph, so there is some debate as to how many cycles equates to "infinite life". Also note the actual value of fatigue limit for an application can be dramatically affected by the conventional de-rating factors of loading, gradient, and surface finish."
Have you seen how much an airplane's wing can flex? Bikes don't bend anywhere near that much. Nobody likes riding a noodle. Five hundred million completley reversed cycles is more than enough in my books.
No, that's not what I'm arguing for, and please don't put words in my mouth (or text in my ummm text box). I'm not banging a drum for any kind of future reality.
I completely agree that buying a hybrid car will change the world - it makes more money for Toyota or the other car producers, who in turn can use that money to either reinvest in hybrid technology, spend it on savvy marketing for hybrid cars, or blow it on a re-entry into Formula One racing (which is also a form of marketing). I don't see what you call 'public policy' contributing anything to that equation, other than having certain US states give our tax rebates for buying a hybrid or electric car.
The point I was trying to make - and maybe the hybrid analogy got off track - was that recycling your aluminum chainring probably makes you feel good, but until INDUSTRY sees profit potential in recycling, energy use reduction, burning less oil, changing to LEDs, what have you... consumer behavior will remain an inconsequential percentage of the total achievable result. The only factor that has PROVEN to make the US consumer use less resources is a shrinking national economy - AKA having less money to spend.
The auto suppliers and their sub-suppliers are eagerly looking toward 2015's reports of continued low oil prices, because it will prod the masses to buy more cars. With low oil and gas prices, do you think people will be more encouraged to buy 1) a more expensive hybrid, or 2) a less expensive conventional car or truck?
We're not necessarily talking about using less resources in this case, but managing resources differently. It would be acceptable to use 10x as much energy if the energy is 100% coming from sustainable infrastructure.
Public policy influences economies as well. When consumer's attitudes towards certain products shift, they stop being bought, and the economy changes. Its not as simple as price.
City governments are pushing strongly towards electric cars especially Beijing, Shanghai and LA, where pollution is a public health problem. They're all already testing electric car sharing programs, and cities (particularly Chinese ones) are trying to remove conventional motors from cities altogether - and since China has a government with actual power, they'll likely succeed if that's what they decide to do.. This public health problem is a public problem, receiving a policy maker response and leading to change in policy. So again, what are you arguing for? Its not a debate about whether or not to cut down consumerism. Its about where the market is going to shift.
Thanks for the discussion. Merry Christmas! VT is nice this time of year.
China is important in free market forces because if they decide to go all out with electric vehicles, the rest of the world will follow suit just because it will be easier to make money that way. But that is besides the point. China is just one example, and it pertained to what we were talking about (the future of the car industry). The same stuff is happening within the United States too, it just doesn't happen as fast, because or political system isn't as efficient (although yes it is less corrupt).
As for aluminum its life span is limited ( no matter how small the force is, it gets weakened every time it is stressed ) and technically much shorter than carbon but as far as recycling goes its almost completely recyclable into the same product over and over. Now for all of you internet engineers out there, yes aluminum has a cycle limit which is stupidly high because they designed the part so, but it will fail no matter what, especially on harder use and crashes which can exceed the stress it is designed to take.... also the aerospace test you see are made by Boeing and the like, do you really think your bike is made out of the same quality of 6061 ( let alone the welding, heat treatment, machining....) ??? nope. Anyways aluminum and steel will always be a better choice over carbon in terms of carbon footprint regardless of recycling techniques because there is a very limited amount of time you can recycle carbon if at all on certain parts and everyone I know who buys carbon parts are so f*ing scared of failure that they change them whenever they see a scuff.... Anyways carbon is a high end product made for high performance, not for carbon footprint and ''eco-friendliness'' so why the hell bother ??? get a smaller car with a roof rack instead of a pick up truck and then you can talk about carbon footprint...
And you know... tools and spares?
Fanny packs were all the rage a few months ago on PB and now packs aren't cool anymore? Sigh... I guess I bought this enduro sash for nothing.
Metal for me Thanx \m/
Mike did make a good point about finding some bars that feel nice though, too many peeps just buy the lightest/ cheapest/ best ano matching/ coolest bars they can find. The biggest difference in bars of similar widths will be the geo and that's what we should look for. For me its Azonic, all day!
I've been considering carbon bars, but now ya'll have got me nervous again.
And now you all think alu is 'safe'.
Whatever. If it's built right it will be fine. The tricky part is knowing who builds their carbon / alu / ti / steel right.
"Scratch the hell" out of an aluminium bar and you'll introduce a whole load of stress raisers that might lead to a crack initiation site and consequently a fatigue failure. This is not good.
This is not a concern with carbon fibre, which is pretty insensitive to fatigue loading and crack propagation.
Over tighten the clamp on a aluminium bar and you might in the worst case cause a little bit of plastic deformation but it's highly unlikely and not a massive concern. Crush a carbon bar and you may cause a bit of matrix failure and delamination. This is not good and may lead to premature bar failure. I expect the problems with sharp edges on stems with carbon bars are not the consequent scratches but the local crushing failure?
So don't scratch your ally bars. And scratching your carbon bars isn't the end of the world. But crushing your carbon bars (or other impact damage) is not a good idea.
When it comes to crashing, sharp impacts on aluminum cause dents whereas they can crack carbon. The dent will create a smaller stress concentration than the crack and you also might not even notice the crack is there. Cracks also arguably lower your moment of inertia more than dents, which would make it worse in bending.
In the end small surface scratches that come from regular use are no concern at all for either material. Bars are certainly designed with this in mind and also with a high factor of safety.
I guess it's really a pick your poison type of thing. Aluminum bars theoretically won't last as long, but you will know it's time for them to go when you look at them after eating it and they are all bent up. Carbon bars would last forever, but if a crack is created they can fail catastrophically and you might never see it coming.
It is also different given the type of composite (thermoset or thermoplastic) and the type of cyclic loading.
A correctly engineered alu or carbon bar will work fine. So in the end it's a trust issue.
My main argument against carbon for freeride applications is that I think components that are critical to you not eating it (such as bars, wheels, or cranks) should be designed for failure such that in the event that the fail the risk of you hurting yourself isn't too elevated. Aluminum parts can be designed to bend prior to fracturing, but carbon parts can't. This applies more to wheels than anything else really, though.
This REALLY helps when you start using I-spec or Matchmaker, as it's hard to get those loose enough to move in a crash without having them migrate from pushing the shift levers.
Which is it?
1. You seem to indicate that scratches on a carbon bar somehow disrupt the integrity of the material. Can you elaborate?
2. Is there some sort of study showing you can carry stuff in the small of your back without being injured in a crash? It seems unsafe.
3.what kind of tape is best to tape your tools to your bike?
Personally, I don't really care, aluminum or carbon for a frame, but for me, there are no downsides to a carbon frame other than cost relative to aluminum.
I'd still not run a carbon bar or seat post (if the days before droppers were still here) even on my road bike.
Carbon snaps with no warning
Aluminum bends meaning you won't have to pay to replace your teeth.
Spank make nice al bars btw
I'd be weary of a carbon frame or wheels due solely to the cost of repair, but a handlebar is a place where it makes a LOT of sense to go carbon, even if you're not on a $5,000+ bike.