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36 votes

Why can't a child bike seat be mounted on a carbon frame?

Carbon tubes tend to be very strong at withstanding forces in the direction they are designed for, but weak at resisting other forces (such as clamping forces compressing the tube), hence why bolts ...
  • 17.4k
23 votes
Accepted

Is it worth buying carbon fiber road bike for short commutes?

Comfort isn't really an issue for a 30-minute ride, as long as the bike fits. Also, for any given price point, an aluminium bike will have better components than a carbon bike, so will probably be ...
18 votes

Does carbon fiber not have a fatigue life?

Fatigue is a concept in metallurgy with a very specific meaning. It is degradation of the crystalline structure of a metal. A metal object or material's fatigue limit is the amount of load it can ...
17 votes
Accepted

Is it safe to ride the carbon bike with a small crack on the bottom of the chain stay? Looks cosmetic but fails the tap test

Only the manufacturer or a competent frame repair person can tell you of it is safe. It does not look just cosmetic to me, but I have no qualification whatsoever. However, this small damage is very ...
16 votes

What do I do when I am unsure if damaged carbon fiber is safe to use or needs replacing or repairing?

Carbon fiber composites are made up of sheets of carbon fiber filaments. These are usually impregnated with resin. To make CF structures, manufacturers will cut up the sheets, then lay them up onto a ...
  • 21.9k
14 votes
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Difference between UD, 3K and 12K carbon finish?

UD, 3K and 12K specify the carbon weave pattern. 3K means there are 3,000 filaments per "tow", 12K means there are 12,000 and UD means unidirectional (no pattern): The construction of bike parts is ...
  • 2,094
14 votes
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Why do bikes have carbon forks?

There are an intersection of a number of reasons: Public Perception - Carbon as that "wow" factor. Colloquial it is associated with "space age" technologies. Therefore it must be better! The ...
  • 30.1k
14 votes

Frame dropout cracked, what can I do? (Allied Alfa Disc / carbon)

A crack, unfortunately, is a crack. That’s dangerous no matter what the material. You could contact Allied to see if you have any options in terms of warranty. However, if you didn’t secure the bike ...
  • 21.9k
13 votes
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Carbon Wheel Heat Bending

To answer your questions No, they are not safe to ride due to risk of the tube blowing out or the tire rolling off the rim. No, I do not think they are repairable (at home). If they were repaired I ...
  • 17.1k
13 votes
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Little "holes" on carbon rims' profile: what are they used for?

They are drain holes to let water out. Light bicycle go into slightly more detail on their webpage: https://www.lightbicycle.com/newsletter/Holes-On-Your-Carbon-Fiber-Rims.html
  • 17.4k
12 votes

carbon vs aluminium frame vibration absorption? bumpiness?

Aluminum has gotten a bit of a bad reputation from the early generation of frames which were overly stiff. This is less the case today as manufacturing technology fixed most of these earlier problems, ...
  • 30.1k
12 votes

Scratch or damage on carbon frame

That's just a light scratch. No issues. if you are worried that the carbon-fiber composite has been damaged by an impact or scratch, the abrasion is far too shallow for that. It has not even ...
12 votes

What's the best way to stow (winter storage) an all-carbon bike?

I don't see a problem hanging a bike from a carbon fiber composite rim. The amplitude of the load would be much, much lower than when riding over even moderate bumps. OK, the load is radially outward ...
12 votes

Are these shallow gouges and imperfections on a new carbon fork steerer benign or serious?

I don't normally go around inspecting fork steerers, but I suspect that's highly abnormal and a significant cause for concern. I don't clearly see torn fibers. If you did, that should mean the steerer ...
  • 21.9k
12 votes

I'm not sure if a torque wrench was used in assembling my carbon bike

He is unlikely to have damaged anything unless he's a complete gorilla. Loosen off any bolts or bolt pairs that you are concerned about, then do them back up to torque.
  • 12k
11 votes
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Can I use brake pads for carbon wheels with aluminum wheels?

In short yes you can, carbon brake pads will stop you but you shouldn't. Firstly the brake pads will not be as effective on the alu rims. Secondly the change between alu and carbon rims could be risky ...
  • 1,066
11 votes
Accepted

Crack in fork or just paint

On the surface it doesn't look good, but I wonder if there is a reinforcement wrap for the brake posts, with an unfinished edge). There are some informal ways to try and confirm whether the structural ...
  • 30.1k
11 votes
Accepted

Does this carbon fork have a crack in it that would make you replace it?

What is visible in the photo is a paint scratch. Letting the bike simply fall over will not structurally damage carbon fiber composite. People seem to think CFC is fragile but it’s really quite robust....
11 votes
Accepted

Chain damaged carbon frame. How to remedy?

It's very likely only cosmetic, but the fine hairline-looking scratches (hopefully only scratches) are not the most common thing to see in damage that occurs from a dropped chain. The other thing to ...
10 votes
Accepted

Do Carbon Wheels Stay True Longer Than Aluminum Wheels?

I give you the following, that you can read here: Talking to Jason Marsh the mechanic of Greg Minaar 2012 DH World Cup Champion about ENVE DH rims (which are carbon), he said that, ”Once you ...
  • 1,290
10 votes

Carbon frame that is designed for strength and durability rather than lightness?

Why produce a heavy but durable carbon frame if one can have a heavy and durable steel frame that is cheaper? Apparently there are no (mass) buyers for such technology. The bicycle industry is mainly ...
10 votes

Crack in fork or just paint

I'm sorry to say that looks like a crack rather than a scratch. Bike looks quite new (I notice the dual pivot calipers), but I believe Trek's lifetime warranty covers CF frames and forks beyond 5 ...
10 votes

Cycled through pothole on carbon frame - damaged?

CFC frames are not as fragile as many people seem to think they are. If you got a heavy jolt but didn't feel like you were going to be thrown off the frame is probably fine. I'd be more immediately ...
10 votes
Accepted

Post crash damage assessment: can I keep this carbon fork and this front wheel?

I can't see the marks on the fork to which you are referring. They may not show up well in photos. The rim brake track appears to have some road-rash damage. I would remove the tyre/tube, and gently ...
  • 106k
10 votes
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Do I need to apply something on thru axle?

I usually put a very small amount of grease on the threads at the end so that it will be easier to remove when you need to take it out again. As with all threaded connections these tend to seize-up ...
  • 923
10 votes
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What's the difference between more or less expensive carbon wheels?

First, I wouldn't recommend buying from Aliexpress brands that you don't know at all. There are some mainland Chinese brands that sell on Aliexpress or other channels that are likely to be trustworthy....
  • 21.9k
9 votes

Does anyone sell a direct-drive recumbent with no handlebars?

I have built a direct drive (geared) recumbent mostly according to Garnet's specifications. The centerpiece is a Pinion gearbox that conviniently has a lot of gears (needed for a recumbent) and an ...
9 votes

Safest way to carry luggage on my carbon frame?

The safest way to carry luggage on a carbon frame is to use a trailer, like the BOB trailers. Carbon frames are very strong, but each area of the frame is designed and tested for the loads it ...
  • 29.5k
9 votes

drilling hole in carbon frame

This is one of those questions where if you have to ask "should I do this?", the answer is "no". Carbon frames need to be specially reinforced (during manufacturing) in the areas ...
  • 1,185
9 votes
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What are these mounts for on inside edge of carbon fiber fork?

They're for full fenders. Many disc road and fitness/urban/hybrid bikes now have them here in order to completely avoid strut interference with the brake. To install the fenders neatly I've been ...

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