Chromoly is slightly heavier than aluminum but the frame can be thinner and has reduced stiffness which provides a smoother ride.
Chromoly vs mild steel chassis.
The chromium adds strength hardenability and a level of corrosion resistance to mild carbon steel though chromoly is not as corrosion resistant as stainless steel.
In this short video tim mcamis explains some of the differences between 4130 chromoly and mild steel tubing for use in drag race chassis construction.
One of the never ending topics of conversation is the use of 4130 steel over mild steel in professional drag racing builds.
In a trail rig like mine i will be using mild steel and a mig.
So if you run a comp buggy 4130 is the way to go.
Aluminum is the second most commonly used material for bicycle manufacturing.
It s lighter and stiffer than steel but it s also more brittle and easily damaged.
Chromoloy tubing is made from a family of low alloy steels that contain chromium and molybdenum sae 4130 or 4140 along with the iron carbon and other elements.
When cost is a factor as for most of us mild steel is a good choice.
If it is mild steel then i have to rebuild the whole thing.
I have a dragster frame and i don t know what it is made of.
4130 is better due to the amount of weight savings you can have with it.
It will still save your life if done right.
If it s chromoly then i just have to replace a couple of struts and add more to my roll cage to bring it to specs.