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What's all this talk about disposable frames?(11 posts)

What's all this talk about disposable frames?niteschaos
Sep 13, 2002 6:31 PM
I heard someone bashing the Scandium frames calling them "disposable." I don't know why just because a frame is lighter than thiers they feel it won't last. True, some companies produce sub-par product, but if you think a frame design leaves Cannondale without being thoroughly fatigue tested, then you haven't done your homework.

Send me those ultralight, ultrastiff and disposable aluminum frames! I'll make good use of them!

Most people I see buy new frames way before they wear out the old one anyways.
re: What's all this talk about disposable frames?eddie m
Sep 13, 2002 6:51 PM
The concern with aluminum frames is that the material is not strong enough to build a frame with the same fatigue life as steel. I think that's why many aluminum frames are harsh- in order to build the frame strong enough, they use more material than would be necessary strictly to have a good riding frame. I also think some of the aluminum frames used by pro teams are discarded after one season. Scandium is only about 10% stronger than other aluminum alloys, so if the frame is lighter it might have a shorter life, but it's probably more economical to replace an aluminum frame every 10,000 miles or so than to buy a titanium frame.
Also tensile strengthPODIUMBOUNDdotCA
Sep 13, 2002 7:30 PM
Eddie made some good points. But aluminum and scandium frames have a lot higher strength per gram than steel or titanium. However, their tensile strength is almost nill. This is what allows the frame that tiny bit of give which soaks up bumps. Steel, titanium and carbon all have almost infinite tensile strength fatigue lifes which allows them to 1) last a heck of a lot longer and 2) soak up the bumps. If you've ever ridden even a couple year old aluminum frame it will be a lot mushier than a brand new one. I experienced this last summer after I was hit by a car and insurance bought me a new almost identical Cannondale. It was cool to see the difference.

urban legenddivve
Sep 13, 2002 8:21 PM
How can it be an urban legend when I've felt it?PODIUMBOUNDdotCA
Sep 13, 2002 8:50 PM
How can it be an Urban Legend when I've felt the difference between two aluminum frames, one I rode about 10,000 km on to one that was brand new?

It should be different with steel since the tensile strength is far superior though and the article illustrated this.

the article tells you how and why. nm.divve
Sep 14, 2002 4:05 AM
Look at this part of the articlePODIUMBOUNDdotCA
Sep 14, 2002 7:48 AM
"The result is clear. In the course of the entire check the frames slowly diminished about a maximum of 4 per cent in the rigidity." 4% is quite a bit... and thats over 5,000 km. Also I'm not sure how the rear triangle was loaded because that could make a significant difference as well. Its not enough to make the bike feel like a wet noodle but it is enough to be noticeable especially if you ride a bike enough that it almost becomes an extension of you.

I recommend that you...divve
Sep 14, 2002 9:05 AM the whole article as such. You cannot draw conclusions by isolating sentences and taking them out of context.

Here's the other part of what you quoted:

"Shortly before the breakage of the frames - with a maximum of 1,000 cycles ("footsteps") before - they become increasingly more flexible. Manfred Otto comments on the result as follows: „During 99 per cent of the time of movement the modifications of the frame rigidity are so small that the cyclist cannot notice it. Only when the additional deflection has already reached a few millimeters, the rider might notice it. Then, if the frame is under load, breaks can be detected already." It should be added that substantial noises often hint at the imminent break of the frame."

In other words, you'll only feel your frame become "soft" just moments before it's going to brake.
Careful with what you feelKerry
Sep 14, 2002 1:11 PM
Unless you put on the same wheels/tires, bar/stem, and saddle (maybe seat post) then comparisons of one frame to another are totally sketchy. Wheels alone can have a tremendous impact in the feel of a bike. At a minimum, you have to have the same wheels under you for any kind of comparison. NOTE: not the same brand/model of wheels, but the same wheels.
Personal experienceSteveS
Sep 14, 2002 4:05 PM
Let's see, I had an aluminum, a carbon fiber composite and a carbon fiber monocoque frame, all of which failed. The interval was about 2 years each for the first two and 3 or so years for the third. If I had paid for all of those frames, I would have been quite chapped. As it was, the producer warranteed all three. Still, in my experience that qualifies them definitely as "disposable" and personally, I would have no interest in buying any of the above materials in used frames. Steel or titanium are entirely a different matter.
Personal experiencebugleboy
Sep 15, 2002 12:55 PM
Are you buying quality frames from a manufacturer that has a good reputation. Smaller companies that rely on others to do their own testing simply don't have the quality of those who do. I have had the same frame materials that you have had. I've crashed in large field races, none of them failed that quickly. what are you doing wrong. Things that make you go "hmmm".