Chromoly frames are better than Aluminum
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Chromoly frames are better than Aluminum
I need help with my senior project. I have chosen the subject of bike frames. My thesis statement is Chromoly frames are better than Aluminum. I could use any help that anyone could give me. I would prefer links to sites where I can recieve information but i would also like peoples opinions. Thanks.
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"Better" is a very subjection frame of reference. People prefer whatever frame material they prefer based on what priority they place on the characteristics of each frame material. Some of those are flex and stiffness, vibration absorbtion, durability, weight, etc. It would be very difficult to say which is better without knowing what you are looking for.
Which is better, a chainsaw or and X-acto knife? Depends. If I want to cut a tree down, the X-acto isn't going to do the job. If I want to cut delicate plastic model parts from the sprue...well the chainsaw will just tear things up. So which is better?
Which is better, a chainsaw or and X-acto knife? Depends. If I want to cut a tree down, the X-acto isn't going to do the job. If I want to cut delicate plastic model parts from the sprue...well the chainsaw will just tear things up. So which is better?
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go to Road forum, search for "steel"
Ziggarat (Ziggurat?) posts a fair amount on the wonders of steel.
Ziggarat (Ziggurat?) posts a fair amount on the wonders of steel.
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#4
Senior Member
Originally Posted by joethebmxer
I would prefer links to sites where I can recieve information but i would also like peoples opinions. Thanks.
Steel vs. aluminum
looking for new bike advice
beryllium bikes?
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If you ride a carbon bike.
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Last edited by DannoXYZ; 02-10-06 at 04:08 AM.
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Originally Posted by joethebmxer
I need help with my senior project. I have chosen the subject of bike frames. My thesis statement is Chromoly frames are better than Aluminum. I could use any help that anyone could give me. I would prefer links to sites where I can recieve information but i would also like peoples opinions. Thanks.
I am a Mountain biker and want a frame to be stiff. Aluminium for me so why do I keep a 10year old chromoly framed bike that gets used a lot? Then why get an ultra stiff alloy frame and put suspension on it? And finally- Chromoly and aluminium are old hat with all the new materials around so why choose either of these in the first place?
Good luck with your project but whatever result you come up with- just talk to the wrong biker and you can be shot down.
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#7
Unique Vintage Steel
lol... nice list Danno!
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Originally Posted by joethebmxer
My thesis statement is Chromoly frames are better than Aluminum.
More elastic, can flex to abosorb big hits
Higher fatique strength, can take more big hits
Can be bent back when tweaked in a crash (can take more plastic deformation before break)
Tubes won't buckle when lightly dented (higher fracture toughness)
Easier to weld/repair when damaged because chromoly air-hardens vs. aluminum which needs to be heat treated
etc, etc...
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You could certainly come up with enough points in favor of steel and against aluminum to write a paper with your thesis, but as a blanket statement "cromoly is better for bicycle frames than aluminum" is bunk. There are amazingly good frames made from each, and utter crap made from each. IMO both steel and aluminum are fantastic materials to make a bicycle frame. Talented designers and craftspersons can maximize the benifts and minimize the weakneses of each material.
#10
Senior Member
Exactly, material properties are irrelevant as geometry, design and construction quality makes a much, much more significant contribution to the final-product. Here's table summarizing the basic properties:
You can use this to come up with some comparison-metrics between the material-properties alone, like:
Stiffness-to-Weight Ratios
105 - chromoly 4130
100 - magnesium ZK21A-F
103 - aluminum 6061-T6
100 - aluminum 7005-T6
98.0 - aluminum 7075-T6
89.5 - titanium 3Al-2.5V
92.6 - titanium 6Al-4V
98.6 - stainless 321
97.5 - stainless Gall-Tough+
659 - beryllium S200F
668 - beryllium SR200
In this case, both chromoly and aluminium are identical. Frames of equal-weights will have equal stiffnesses in both materials. Or you can analyze based upon:
Yield Strength-to-Weight Ratios
184 - chromoly 4130
402 - magnesium ZK21A-F
379 - aluminum 6061-T6
421 - aluminum 7005-T6
716 - aluminum 7075-T6
448 - titanium 3Al-2.5V
679 - titanium 6Al-4V
208 - stainless 321
701 - stainless Gall-Tough+
524 - beryllium S200F
751 - beryllium SR200
This will let you make comparison of frames of equal-weight or equal-strength. Aluminium outpaces chromoly by a significant margin. For the same strength, aluminium will be lighter than chromoly. Or for the same weight, aluminium will be many times stronger. Chromoly's day as the premiere frame-material has long passed. Modern high-strength stainless-steels on the other hand...
Check out Damon Rinard's FEA analysis of frame structures:
Finite-Element Structural Analysis: A New Tool for Bicycle Frame Design
12 High End Frames in the EFBe Fatigue Test <-- actual testing of frames to failure
Note the cycles these frames were subjected to before they broke. Note the frames with the lowest number of cycles at failure. Then note the frames that did not fail at all after 200,000 stress cycles...
You can use this to come up with some comparison-metrics between the material-properties alone, like:
Stiffness-to-Weight Ratios
105 - chromoly 4130
100 - magnesium ZK21A-F
103 - aluminum 6061-T6
100 - aluminum 7005-T6
98.0 - aluminum 7075-T6
89.5 - titanium 3Al-2.5V
92.6 - titanium 6Al-4V
98.6 - stainless 321
97.5 - stainless Gall-Tough+
659 - beryllium S200F
668 - beryllium SR200
In this case, both chromoly and aluminium are identical. Frames of equal-weights will have equal stiffnesses in both materials. Or you can analyze based upon:
Yield Strength-to-Weight Ratios
184 - chromoly 4130
402 - magnesium ZK21A-F
379 - aluminum 6061-T6
421 - aluminum 7005-T6
716 - aluminum 7075-T6
448 - titanium 3Al-2.5V
679 - titanium 6Al-4V
208 - stainless 321
701 - stainless Gall-Tough+
524 - beryllium S200F
751 - beryllium SR200
This will let you make comparison of frames of equal-weight or equal-strength. Aluminium outpaces chromoly by a significant margin. For the same strength, aluminium will be lighter than chromoly. Or for the same weight, aluminium will be many times stronger. Chromoly's day as the premiere frame-material has long passed. Modern high-strength stainless-steels on the other hand...
Check out Damon Rinard's FEA analysis of frame structures:
Finite-Element Structural Analysis: A New Tool for Bicycle Frame Design
12 High End Frames in the EFBe Fatigue Test <-- actual testing of frames to failure
Note the cycles these frames were subjected to before they broke. Note the frames with the lowest number of cycles at failure. Then note the frames that did not fail at all after 200,000 stress cycles...
Last edited by DannoXYZ; 02-10-06 at 04:02 AM.
#13
Senior Member
Hitting pot-holes and deep drainage ditches can load the up the frame with 4-5 Gs, 600-900lbs of force. By the time you hit an aluminium frame hard enough to bend it, the chromoly will have been completely twisted into a paper-clip!
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Bog std chromoly is hardly a cutting edge material. The specialist heat-treated steels outperform chromoly by a huge margin. Check out the reynolds website for the specs.