Hot answers tagged

35

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 for carbon bars, seat posts etc are usually only torqued to 4-5Nm.


33

While some will say "it's just supply and demand" and companies charge "whatever the market will bear", I'm not convinced that your comparison is fair to try and determine whether bikes are overpriced relative to motorcycles. Using a $4,000+ road bike and comparing it to a $3,000 motorcycle is comparing the upper end of one product to the lower end of ...


23

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 more enjoyable to ride. For a commuter bike, I'd be much more worried about theft and damage, unless you have somewhere secure to park the bike at work. If you ...


15

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 ...


14

@Gary Has a valid view on the answer, but its also a bit more complicated than that. He has compared a 250 motorbike to a 1000cc motor bike - completely different to comparing a $500 road bike to a $5000 road bike. A better comparison is a 250 GP Motorbike vs a 250 Sports bike vs a 250 Commuter..... Unlike motorcycling, Road Cycling is the new Golf. As a ...


13

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 would not trust them again. I believe that this item is not fit for the purpose of a bicycle wheel. It should be returned to the place of purchase on those ...


13

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 always UD, only the top layer when naked can be specified to these different finish types. Also there is usually an option to choose between matte or glossy. ...


13

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 penetrated through the paint. It's not a crack because cracks do no start in the middle of frame tubes, they propagate from edges or holes.


12

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, and bicycle designers can create formed aluminum tubes that provide compliance (i.e., vibration absorption) in one direction (e.g., vertical compliance) and ...


11

Short answer: No. Long Answer: I would not use carbon rims for commuting for several reasons: They make the bike look more shiny than you want, attracting all kinds of unwanted attention. I ride my commuter bike in any weather without too much maintenance. Should the carbon rim fail at some point, I at least won't notice a hairline crack until the wheel ...


11

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 truth is that the performance of carbon depends heavily on manufacturing techniques used (e.g., materials and layup). See point 3 for an example. Weight - Carbon ...


11

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 to your carbon wheels, a tiny fragment of alu from the training wheels could damage your carbon rims (source: Swiss stop website). So to answer your question ...


11

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 carbon has been damaged. 'Carbon usually has a very crisp sound to it [when tapped] and when it’s damaged the tone changes completely,' says John Hansell of ...


10

@DWGKNZ was right, turned out that there was a 3mm hex at the bottom. Picture of the removed plug, upside down: Thanks for quick and useful advice.


10

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 have built them, you don’t need to do anything, the spokes remain tight and they don’t need truing and we use a lot less through the year as they are ...


10

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 driven by the competitive cycling needs, whether it is good or bad for a regular consumer. The choice of frame material is driven by the material properties ...


10

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 years anyway.


10

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 concerned about the wheels than the frame, and that may be the source of the rattle. You can examine the frame closely looking for cracks. If it's dirty clean it ...


9

Carbon is seen as expensive and light while Aluminum is heavier and cheaper. Both are, to all practical purposes, more than robust enough for the job. At the price point you are looking at (for a hard tail), Carbon is a no brainier and superior in every way. If you are worried about failure mode, both are as likely to fail catastrophically as each other, ...


9

I have never had or heard of a problem. Over at www.velominati.com, one of the rules is Rule #80 // Always be Casually Deliberate. Waiting for others pre-ride or at the start line pre-race, you must be tranquilo, resting on your top tube thusly. This may be extended to any time one is aboard the bike, but not riding it, such as at stop lights. While some ...


9

Any Shimano compatible 10-speed wheel, other than a very few with special deep-splined aluminum freehubs such as WH-7800, can take any 9 speed Shimano cassette without additional spacers. Shimano 11 speed road freehub bodies are longer and require a common 1.8mm conversion spacer to put a 10/9/8 speed cassette on. Many wheels come with this spacer, or a ...


9

Doesn’t look like a crack, looks more like a surface void that formed during the resin injection molding. These types of imperfections are not uncommon, especially on the inside of the frame where you can’t see them. Less common to see them on the outside as they are usually caught in quality control inspections. While they are not ideal, as areas with ...


8

Carbon fiber often stands up to higher stresses than comparable aluminum or steel frames. You really have nothing to be worried about as long as you are buying from a reputable manufacturer. Check out this video for more info: Santa Cruz tests carbon vs aluminum frames You'll notice that aluminum fails under much less stress than carbon does in almost ...


8

Ask yourself this- would you buy a car off of Alibaba to save a few bucks, or would you fork over a little more money and buy a Honda/Toyota/whatever? Buy the name brand bike. If your Alibaba bike's headtube snaps off on a gnarly high speed descent, who's going to do something about it? Not Alibaba, and good luck getting the manufacturer from god knows ...


8

To the best of my knowledge there are no suitable direct-drive hubs available commercially, which means that there are no bikes sold that use them. Schlumpf make a unicycle direct drive hub that offers 1:1 and 1:1.55 gears, but for a recumbent bike those ratios would be ridiculously low. Also, it's obviously fixed gear so without a freewheel it would be even ...


8

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 expects from a given direction. Adding luggage to a frame not designed for it, i.e. Without braze-one or threaded mounts, is generally a bad idea.


8

Most of that damage is through the paint, but there are obviously some gouges in the surface of the carbon fiber composite itself. I think if you want to be sure that a repair is good you will have to consult a professional CFC repair shop. Chances are they can sand off the paint, smooth the area and lay a patch over the damage.


7

For Aero seatposts, smack the saddle nose solidly sideways with your hand, you should hear a loud crack, this is the surface tension breaking. Seatpost should then move OK. Saw this done by ex-Pro who was Giant dealer on a Propel, made my life so much easier since I learned that tip


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 ...


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 ...


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