Hot answers tagged carbon
21
Carbon fiber isn't necessarily a "weak" or "fragile" material. If you had a tube of the same diameter and thickness of typical CF as a typical steel frame tube, that CF tube would be extremely strong and durable.
Metals like steel and aluminum are isotropic materials. That means their mechanical properties are identical in all directions. If you have a cube ...
18
First a disclaimer: most of what I know about carbon fiber fabrication comes from aircraft, not bicycles. Also note that carbon fiber is not the only composite that gets used -- just for one alternative, Kevlar fibers can be useful as well (Kevlar is stronger, but also more flexible than carbon).
Carbon fiber is strong, but does not respond well to point ...
16
Absent some kind of abuse or extraordinary stress (like falling on top of the bike while it's lying on the ground - stressing the tubes from the side, riding with a friend sitting on the top tube...) a carbon fiber frame should outlast the rider.
Lennard Zinn covered durability of Carbon Forks for Velo News a while back. Here are some quotes from that ...
9
As the person who made that claim, the reason is that allegedly some greases can attack the epoxies found in some carbon fiber applications, causing a breakdown of the CF structure, and causing expansion which will jam the post in place.
The epoxy will otherwise not corrode, so it's not necessary for that purpose. The manufacturers also recommend you do not ...
8
If this is the kind you have, then leaving the bike in there should make no difference whatsoever. This trainer clamps onto the rear axle, it doesn't even touch the frame. When you're off the bike, the frame doesn't have to do anything except support its own weight - there's no possible way it could get damaged.
You're probably less likely to damage the ...
8
Carbon fiber is stronger, and far less susceptible to fatigue than any other frame material on the market. It can be engineered to have the strength of titanium, the ride quality of steel, and the stiff and powerful performance of aluminum at the same time.
I have only broken 2 frames in my life. Both were aluminum, ridden far beyond the fatigue life of ...
8
Watch the Tour de France...you'd be hard pressed to find a bike that is not carbon. Yes pros do get multiple steeds, but remember riding is their full time job. When was the last time one of us put 30-50 hours on a bike in a given week, never mind for 6-8 months! Now think about the wattage these guys put out and hopefully you are getting the idea...that ...
8
Carbon parts will cause aluminum to oxidize, as a chemical reaction which is why seat posts wind up stuck in frames. But that isn't why this is necessary.
"Carbon grease" is not actually grease. It's a friction compound which increases the friction between your fancy carbon seat post and your frame. Increasing the friction allows a lower torque on the ...
8
That dimension refers to the depth of the rim. See this article on some particular carbon rims, that includes a cross-sectional diagram. Deeper wheels tend to be more aerodynamic, though they are heavier, and handle worse in crosswinds. Thus, different rim depths are more suitable for different types of races. 88mm rims are almost exclusively used in ...
7
I've mounted lights with similar clamps on carbon forks with no ill effect (just have to be very careful not to over-tighten the clamp) but a lock -- which is heavy -- might put a too much torque on such a small clamp. Maybe if you could spread out the area over which the clamp attaches to the frame then it might be ok.
What about attaching the U-lock ...
7
If it were a steel frame and fork there would be no question -- steel lasts nearly forever, even when moderately rusty, and can take all sorts of abuse.
Aluminum is a bit less robust, but if it only has "a few thousand" miles on it (and not 30,000) and has not been abused (or hit by a car) then it should be good. The problem with aluminum is that it can ...
7
At the shop we generally use a "normal" hacksaw blade. I'd go with finer blade (more teeth per inch) if there's an option. Go slow and smooth (long low pressure strokes) and keep the blade perpendicular to the bars. The tape will probably help but do take care removing the tape or you might cause the fray you're trying to avoid.
There are special carbon ...
6
In general, you've hit the high points yourself.
The benefits (and issues) will vary by post model, manufacturer, and design. Carbon fiber is a very versatile material engineering wise.
Storck makes 2 carbon posts, which are externally identical. But one is a comfort post, which focuses solely on smoothing out your ride, and the other focuses on being ...
6
That is purely marketing. It's a common ploy with components, but I've never seen it on an entire frame until now. Aluminum and carbon can be used in conjunction effectively, but not in this case. The carbon wrap on that bike is basically veneer. While Schwinn was once upon a time a well respected brand, they suffered a major fall from grace after going ...
6
General rule of thumb, a stiffer frame will absorb less of the input energy and transfer more energy - hence more power from you legs means more power to the wheel.
But....
The bikes have different designs, so the aerodynamics of the bikes and the rider on them will be different which will result in different speeds.
And then...
A stiff frame will ...
5
Personally, no, I have not had any problems w/ carbon fibre mountain bikes. I am currently on my 5th such steed (Trek Fuel EX 9.8) and it is going quite well. My thumb ... not so well. But, that's besides the point. Of note ... I weigh 145 lbs and ride the bike for what it is meant.
I have seen many broken carbon frames. Like wise I have seen many broken ...
5
Markus Storck, lead engineer and owner of German carbon frame powerhouse Storck Bicycles, told me at a conference about 3 months ago that the best ways to tell if a frame is cracked are movement and time.
Movement, because a crack will flex if it's through the paint into the carbon, and you put pressure on the center of the crack, and time, because a crack ...
5
That is unlikely. The inside of a frame is machined/molded to a specific size for the seat post. An integrated post is not finished internally. Also, it is unlikely that the internal and external diameters of the post/frame/clamp would match well enough to be ridden safely.
Seat post fitting is a zero tolerance game, and they are dimension-ed to the tenth ...
5
Do you know the history of the bicycle (crashed, etc)?
While bicycle geometry\components\preferences have changed over the last 12 years, the life span of well cared for aluminum frame and carbon fork are much longer.
Clean the frame and fork and give it a thorough examination. Look for:
Major dents in the frame that may compromise the integrity (minor ...
4
For the carbon fiber to be of any use structurally, it has have multiple layers. If it says it is wrapped around the aluminum, my bet it is for show only so it gives the appearance of being an expensive frame when it is clearly not.
There is no way that a composite of the two will be very light without being very weak if it were compared to a full Carbon ...
4
I would be concerned. The bottom bracket is the most heavily stressed part of any bike, and carbon has a catastrophic failure mode--that is, you don't get any warning. One minute it seems fine, the next minute, you've got carbon-fiber shrapnel.
As a first measure, I might clean it up as best as I can, take some pictures, and send them to the manufacturer or ...
4
Assuming the stem was chosen by the manufacturer, it's required torque as printed on the stem should be within the ability of the fork steerer to support.
If the stem says,"Max Torque 10Nm" as opposed to just "10Nm" then start with a lower setting around 6Nm and work up slowly until the stem clamp will not slip on the steerer. If only the number is ...
4
It's likely that Sheldon's concern was for galvanic corrosion between carbon fiber and aluminum. This is an issue that's well-trod in both the bicycle and aeronautics fields. In essence, in the presence of an electrolyte (sea air, your sweat) and a cathode (carbon fiber-embedded resin) the anode (aluminum) will corrode. In the case of a seatpost/seattube ...
4
Never use a hammer.
In order to check the inside of the frame, visual inspection most times FAIL, because the problem is caused by tiny bumps or misalignments that are not easily seen with naked eye and even felt with fingertips.
I would recommend that you take another seatpost (an old one you can take/borrow on a local bike shop) and try to insert more ...
3
Carbon compound can definitely help. As the following link points out, it helps you avoid 'over torquing' to ensure that the component doesn't slip.
http://www.finishlineusa.com/products/fiber_grip.htm
In my personal domain, if there is carbon and carbon, or carbon and some other material, thou must use fiber grip. And a torque wrench. No questions.
3
Carbon fiber is a very strong material, but like any material it does some things better than others. From Wikipedia:
Carbon fiber is very strong when stretched or bent, but weak when compressed or exposed to high shock (e.g. a carbon fiber bar is extremely difficult to bend, but will crack easily if hit with a hammer).
Considering that a carbon fiber ...
3
Try to push the seat down slightly.The carbon weave can act the way those finger cuff toys we had as children did (the more you pull the tighter they get).By pushing down you release the grabbing action.Make sure you use something similar to Park Tool Carbon/Alloy Assembly Lube before you reassemble it,check with your local bike shop for their ...
3
I just found this from a carbon fiber leaf spring manufacturer...
In comparison with steel leaf springs they have significantly greater
spring action, higher internal damping and a more balanced springing
behaviour, with a many times greater retention capacity of elastic
energy than spring steel.
...
3
The Park Tool BBB-2 lists the recommended torque for side/dual/center pull Shimano brakes as a range from 7.84-9.8 Nm. I see no specific mention for carbon frames/forks. Bicycle tutor has a similar table here: http://bicycletutor.com/torque-specifications/
2
As far as I know carbon is most prone to catastrophic failure of all frame materials. Depending on the type of separation you see it could be a bit dangerous to keep on using your bike as is. The catastrophic failure occurs because the epoxy becomes brittle over time. A new layer will probably extend the life of your frame just by protecting the original ...
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