Originally Posted by
SlimRider
This statement is so inaccurate, is almost hilarious. The bayer process, is a much more expensive process. Extracting aluminum from bauxite is a more expensive process than the extraction of iron from its ore to make steel. Alternatively, recycling aluminum is cheaper and less complexed than recycling steel. Also, aluminum is much more readily available.
You may want to go back and reread what I posted. I said
exactly the same thing you just did.
Originally Posted by
SlimRider
Poppycock!
Steel is much heavier than Aluminum. Raw materials and their products ship by weight. Therefore, it costs more to ship steel than aluminum. Industrial profiteers understand this fact, and make modifications, accordingly. Even if the savings were just a a few pennies on the dollar, the bicycle industry would save millions simply by making the transition from steel to aluminum. That's the real reason that we're all riding aluminum bikes. It's because of industrial profiteering, it's not due to bicyclists taste in frames changing.It most certainly is not due to the bicycle industry wanting to provide cyclists with a better and more efficient bicycle. Besides, most bicyclists initially suspected that aluminum frames had their misgivings. As it turns out, they were right!
Yep. Costs more to ship raw steel than raw aluminum. But, as finished products, the weight differential isn't enough to have much of an impact on shipping costs
for bicycles.
But if you have to power the machine with a weak power plant, i.e. a human with ~1/4 of a horse power, the weight of the machine becomes very important. Why do you think we are
so obsessed with weight?
Originally Posted by
SlimRider
In most instances, there's only two to four pounds difference between a racing road bike made of carbon and a racing road bike made of aluminum or steel. I don't know where you got your information.
Two to four pounds is huge! And I get my information from the densities of the materials. Steel weighs 3 times as much as an equivalent volume of aluminum. The volume of material to make a bike of the same size and geometry are almost equivalent. You can shave some volume from steel, or conversely, add some volume for aluminum to account for the strength of the materials. But if you melt the bike down and measure the volume, you'll only differ by a few percent.
Originally Posted by
SlimRider
I don't know what planet your steel comes from, but steel almost always tears or bends, before it breaks. That's not something we can say about aluminum. Aluminum has a very low yield capacity, making it more susceptible to breaking or snapping. To that extent, you've the two metal's roles of behavior, reversed. Thus far I've owned about about a dozen bicycles in my entire life. I've never had one to fail on me. All of my bikes have been made of steel. I currently own a Trek 7.5FX. It's frame is aluminum and it's doing quite fine.
Seriously? "Steel almost always tears or bends before it breaks"? Ever broken a pedal spindle? They don't bend. They just break. Ever broken a spoke? Again, they go 'ping' and are broken. I've broken frames and the steel ones never tore nor bent before they broke. They snapped. The aluminum ones cracked and creaked and tore apart but they didn't 'snap'. Even an aluminum that was made to be very stiff (Specialized M2) didn't just snap. Cracks propagated from stress risers but they 'snap'.
Now how is it that you have "personally witnessed larger numbers of failed aluminum frames than steel frames" and you've never broken a frame?
Originally Posted by
SlimRider
Well that hasn't ever been my experience. I've always seen many more failed aluminum frames than steel frames. I've also always heard more rumors about associates aluminum frames failing. Haven't heard much about steel frames failing. The only type of frame failure steel bikes seem to have is derived from the result of accidents.
- Slim
You need to get out more. Steel frames can fail through more modes than "derived from...accidents". From my personal...and I mean 'it happened to me'...experience, I've had steel failures at the dropout, at the steer tube on the fork and at the bottom bracket bridge, twice. Even after repair, the bottom bracket bridge broke again outside the weld area. I've also had axle failures, pedal spindle failures, spoke failures, bolt failures, etc. all of which, including the frame failures, were rapid failures.
I've also experienced aluminum part failures such as rims and cranks. I've had rims crack down the middle of the rim and I've had the sidewalls break as well as cracks around the spokes and mild spoke pullouts. The cracks down the middle of the rim are perfect examples of the failure mode of aluminum. The tire pressure...these were all narrow mountain bike rims running wide mountain bike tires...bows the rim outward and pulls the middle of the rim apart. The aluminum 'tears' from spoke hole to spoke hole exactly like these rims.
Picture borrowed from here
If you look closely at the picture, you can see crack propagating from one spoke hole to the next. But you can also see cracks propagating past spoke holes. If the failure mode was sudden, the large spoke hole should have stopped the crack but it didn't. The cracks are the result of the aluminum tearing due to the outward force placed on it by the tire's air pressure.