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34

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 ...


28

This is downright dangerous and should never be done on a bicycle someone intends to ride. The top tube is integral to the strength of the bike. The frame can buckle or worse when you try to ride it. First, make sure you're looking at the right size of frame. If its too big, it's going to be hard to get on and off from. You can buy a stepthrough frame or a ...


27

I think the simple reason is that the drivechain hadn't been invented. In 1818 the dandy-horse or draisine was invented. This was similar in shape to a modern bicycle, but without pedals. Riders would scoot along with their feet. If you want to go a bit faster, especially on any kind of incline, then you need a better way of putting power in. Without a ...


24

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 ...


24

For a standard bike in normal use you should not, from the seat, be able to touch the ground (without leaning, or except, perhaps, on extreme tip-toe). A standard diamond frame (with horizontal top bar), for road use, should be sized so that you can stand flat-footed over the top bar with a "comfortable" margin (but no more) between the bar and the stuff ...


22

Other than the obvious fact that your better quality (and better handling) bikes tend to be lighter, there's no real correlation between weight and performance (other than a modest effect on acceleration and the obvious effect on hill climbing). But you can generally (with some exceptions) assume that a bike that is quite a bit (like 2x) heavier than others ...


22

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 ...


20

Way back when safety bike were becoming popular women wore skirts. Skirt lengths were to the ankle. The dropped top bar made getting on possible while maintaining resectability. Women were considered to fragile to risk hitting the top tube hence the slanted bar. The trend continued even long after women stopped riding in long skirts. Modern WSD (women ...


18

From metallurgy for cyclists: a tube's diameter increases (D), the stiffness increases to the third power of that number (d is the inside diameter). Comparing a one-inch tube and a two-inch tube of equal wall thickness., the fatty is going to be eight times as stiff as the little weenie tube. And the weight will only double. Now does the ride of those ...


18

Yes it will damage the bike. Frames that have that top tube rely on that bar for structural integrity. Other bikes with step through frames are built to add rigidity elsewhere.


17

The best method for handling exterior frame rust depends on how much time you'd like to invest. The difference comes down to what you use to complete the two basic steps: Remove the rust Good: Sandpaper - Cheap, but wont remove all the rust, and may leave debris. Better: Steel Wool - Will remove most of the rust, but may leave steel wool fragments, which ...


17

Before you take any more forceful measures, it may be a good idea to think a little about chemistry: 'Rust' is typically the name put on any type of corrosion, but technically & specifically, it is the corrosion of iron (or steel) to form iron-oxides. Although your bicycle is most definitely steel, your seatpost is not -- it's aluminum-alloy, which ...


17

It only seems strange to you because you've had the benefit of never having to learn the lessons of the penny farthing and the technological achievements of the safety bicycle firsthand (aka 'standing on the shoulders of giants syndrome'). The penny farthing is only awkward and dangerous because you are comparing it against a technological leap forward. ...


16

Steel is still very common for relatively expensive "touring" bikes (bikes intended for long distances carrying panniers). The slight additional weight of a steel frame over aluminum (well less than 10 pounds in most cases) is inconsequential when you have 40-100 pounds of gear on the bike, the bike is more durable, and the flexibility of a steel bike is ...


16

Some things differ if you are looking at a new or a used frame, but here are some suggestions: First, when you say you are looking for a steel frame, what you probably mean is a ChroMoly Steel alloy frame. This would be a frame made from tubes where chromium and molybdenum were added as the steel was refined. Frequently you will see a sticker on the tube ...


15

Yes, frames do fail even if they're not crashed or ridden excessively harshly. The only way to mitigate this problem is to inspect the frame regularly during your maintenance and cleaning. Look for cracks. When riding, pay attention to creaks and squeeks and always find the root cause (it could be a crack). Keep in mind that: A bad weld could hold fine ...


14

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 ...


13

I had a similar problem on my Pugsley, though it was under braking (discs) that I was kicking the wheel around in the dropouts. After talking with the guys at my LBS, I learned that I wasn't putting enough force into the quick release. They said that a good, tight, clamp should leave an imprint of the lever on your palm when you close it. It will be ...


13

The seat tube is split because it has rear suspension - the rear of the bike rotates around a pivot located just in front of the bottom bracket. Several early full-suspension bikes used a similar design for the rear pivot; this design was then knocked off by the lower-end manufacturers looking to cash in on the popularity of mountain bikes. It's extremely ...


13

Strength at high speed? I have ridden my road frame for 2 years now, and have many miles on it. One of my favorite rides takes me to a hilly section where I have a long sweeping downhill. On a good day, I can reach 70 km/hour. At the bottom is a bit of a tight bend where lateral forces are a plenty. The joints and the bamboo are holding up better than I ...


13

I see frame geometry having 3 primary affects Fitting the rider; which you're already addressing and I won't talk about here... But a lot of geometry stuff comes down to making the other stuff work with fitting riders on the bikes. It's very important. Fitting stuff on the bike Handling characteristics. Since you asked, I'm talking about your basic ...


12

In the near term it's reasonably safe -- the dent is not sufficiently deep to seriously weaken the tube (though one does need to be concerned about the integrity of the welds on the rest of the bike, given it's been in an accident). In the far term (10s of thousands of miles) there's danger that the tube will fatigue and become weakened at the dent. (The ...


12

It is very likely that you are putting too much stress on the frame when you are cycling due to your power stroke. It took me a long time to train myself to avoid standing and powering the bike through the acceleration of starts, or even powering through it while sitting. I've long since learned that while I have plenty of power, I actually am able to ...


12

With a smaller frame, you will need an appropriately longer handlebar stem in order to retain the cockpit length. This will affect handling of the bike: it will feel more "lively", which can be good in some cases (tight turns, difficult terrain) or bad (less stable) - in most cases. A smaller frame will be marginally less reliable, and more prone to break, ...


12

A few things that you can look for, some already mentioned in other answers: Tubing, as other have mentioned, higher quality frames are made of higher quality tubing. High quality tubing will often be a tube set from a "name brand" and have the appropriate stickers (e.g. Reynolds 531). High quality tubing is typically double, or even triple butted - i.e. ...


12

A few tips: Painters don't know anything about bikes. If the paint shop is not specifically a bicycle paint shop, they may still offer to strip your bike of components for you. Don't let this happen! Most painters are unfamiliar with the intricacies of bicycle mechanics, and may improperly remove or damage some components, or not know or have the tools to ...


12

I thought this was an interesting question, so first of all, +1. First off, the sloping tube (your second image) is known in cycling parlance as a compact frame. I found an article on the Giant web site about the advantages of a compact frame. When I say "advantages" - this is Giant's word not mine! The full article is here, but to summarise it: the ...


11

I have toured a bit, both on steel and aluminum. I have also read a lot about the classic pros and cons perfectly explained by DanielRHicks. So, based on study and personal experience, I would tell the overal quality and specificity of the bike is much more important than the material itself, for these reasons: Weight difference is irrelevant since you ...



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