Frame Materials
 

Hey guys, so in my research to find a new bike frame im finding lots of different materials being thrown around... and after trying to find things on these forums with no avail i assumed I would make a post...

So Im looking into new frame sets, and asides from what that little remarks i read on here about Chromoly Frames or aluminum or whatever I have no idea what the advantages or disadvantages are for the most part... Some common frame material I've been seeing is... (off the top of my head)

Chromoly 4130
Reynolds 631 Steel
Reynolds 530 Steel
Assorted Aluminums

It seems like the Reynolds frames are the lightest, but is it the strongest? Theres alot of talk about Chromoly being preferred in most cases... is the true? any information helps.

I went through that and got a little bit of information, but it doesnt do a good job of comparing the Chromoly to the Reynolds, but ill post the impression I got of these metals, please correct me if im wrong.

Chromoly 4130 - Newish, most popular frame, pretty dense and heavier than Reynolds 631... No noticeable flex in the frame under normal conditions.
Reynolds 631 Steel - upgrade from the older more common 530 steel, Lighter that Chromoly, low density, a little bit of "liveliness" in the frame, Air hardened (which if i remember correctly from shop classes way back when, allows the frame to flex more. aka Reduces stiffness)
Reynolds 530 Steel - Popular a few years ago, pretty similar to Chromoly 4130
Alluminum - Lighter, less dense, less strength, more flex, cheaper, etc

Does this sound about right? and to put this in perspective Im looking at a Kilo TT (reynolds 5321/Chromoly 4130) and a IRO Mark V (reynolds 631)... I know the frameset for the Iro ways 4 lbs, how much in comparison would the Kilo be?

Also does weather take its toll on either of these materials more than the other, I live in Chicago so this frame is going to take quite a beating of rain, heat, cold, ice, snow, sleet, salt, humidity, etc.

Steels have the same density.

The different types of steel are lighter because the higher-end tubesets are stronger and can be highly butted and made thinner than the lower-end tubes. Straight gauge Reynolds 853 is the same weight as straight gauge 4130.

Good to know, I guess when i said density I meant the tube is generally thinner, im probably still incorrect though... thanks for the clarification

EDIT:Okay so 853 is a decent bit heavier than 631 then, besides the weights is it safe to say chromoly is a much stiffer frame?

Are you strong enough to flex the frame?

absolutely not, im not so much worried about me flexing it, Im more worried about how it rides... We have very rough streets in most parts of chicago, and i dont want to feel like im riding a pogo stick around town... also i want something that is going to be able to survive the elements, and being out in the elements for hours at a time

A flexier frame will actually be more comfortable and will dampen road vibrations.

noted, and as for weather is chromoly any better than reynolds or is that primarily based on the paints and coatings used?

As per the late and great Sheldon Brown:

Stiffness

Stiffness affects the riding qualities of a bike frame, since a frame suffers no permanent deformation in normal riding.
Stiffness is determined by a property of the material called "elastic modulus" Elastic modulus is essentially independent of the quality or alloying elements in a given metal. All kinds of steel, for instance have basically the same elastic modulus.

and regarding how they weather, its steel, so it will rust if you don't take care of it.

Wipe it down when it needs it, frame saver on the inside would be a plus, when the clear coat wears down give it another.

No difference. Reynolds is just a brand name. Chromo is just a type of steel chemistry. What matters most is the geometry, diameter and shape of the tubing, butting of the tubing and quality of the welding. I have a lot of Chromo bike frames and they are quite different, even though the material is essentially the same.

Alrighty thanks so much for the help, questions answered!

All steels have the same mass and/or densities. Chromoly steel has been made stronger than carbon (hi-tensile) steel, by the alloying of iron. This requires the addition of the elements molybdenum and chromium. Since these steels (which are alloys of iron) have been made stronger by these additions, they can be butted, or made thicker at the ends, where they are joined. This is true, because that's where most of the stress will be experienced by each bicycle. Butting is usually achieved by making the middle portion of a tube, thinner than at the ends. This is done to make the overall bicycle lighter in mass. It therefore, is performed mostly upon road racing bikes, and not so much with hybrids, cruisers, and mountain bikes.

There is a distinct difference between hi tensile steel and chromoly steel. Hi tensile steel is not as strong as chromoly steel. It is also more susceptible to rust or oxidation. It is however, almost as durable, and can be made to be just as strong as chromoly steel, by making the tubular walls thicker, or by increasing the diameter of the tubes.

Chromoly 853 is the same as 4130 chromoly steel, except that it has to go through an air-hardening process, to acquire its strength. 631 chromoly is almost as strong as 853 chromoly, but not quite. The stronger the steel, the more it can be butted, and the less it will weigh when racing. Therefore, 853 chromoly bicycle tubes can be made thinner than 631 chromoly tubes. Both types of chromoly bicycle tubes, can be made to be thinner than 4130 chromoly tubes. All chromoly tubes can be made thinner than hi-tensile steel bicycle tubes.

Whenever looking for a steel bicycle frame, always buy chromoly! :thumb:

Read this if anything else comes up. His website is a textbook.

http://sheldonbrown.com/frame-materials.html

If you were making a track bike and you had the torque of a 250lb track rider chromoly would be the stiffest, strongest material, but, the streets of Chicago will not humble the frame, they may humble the rims, depends on if you keep enough air in your tires. So, why not carbon fiber or titanium? What matters most, as was mentioned, is the angles of the frame, if it's stiff, it'll ride stiff, if it's soft, it'll ride soft, that's how it'll feel to the rider, the frame won't feel the bumps, the rider will, and the rider can adjust, get off the seat when a big bump is coming, as a matter of fact, jump it...

What?

853 and 631 have the same density. A 1cm*1cm*1cm block of 853 weighs the same as the same sized block of 631.

853 has a higher UTS. It is stronger. The 853 tube can be made thinner and still have the same strength as a similar 631 tube.

You are better off asking around in the Frame building section if this forum . Guys that actually build stuff

Why bother them? This is too trivial....

Aluminum VS. Steel
 

We've already had the Aluminum vs Steel discussion.